Author: Arunava Chatterjee, INFS Expert scholar
The issue of loss in muscle strength and power, mobility, response time to real world conditions and difficulty in performing activities of daily living are some of the important health related issues facing the elderly after age of fifty, which affect both sexes equally. Typically, over this age subjects are prone to fall prey to sarcopenia and reduction of strength and even more of power, not only due to the decrease in muscle mass but also because the decrease in more in Type II type of muscle fibers. This causes severe lack of independence in ADL (activities of Daily Living) (Joseph F Signorile 2007). and may be cause of serious injuries due to fall. The effort of this study was to do a partial review of the research done till now on effect of strength and power training on older adults, to have a deeper understanding of key issues and to reach some inferential consensus of the same. The review came up with the conclusion that sarcopenia related conditions in elderly can be tackled with timely intervention with proper exercise scheduling which contain elements of both power and strength training. This will help the seniors in positively dealing with the effects of sarcopenia. Proper nutrition and micronutrient supplementation will also play a role in getting increased benefits from training.
Through their study, Mizko et al. 2003 tried to ascertain the relative efficacy of power vs strength training as a means to ensure whole body functionality in older adults and by studying the change in anaerobic power and muscle strength with change in physical functionality. In a study comprising adults with mean age of 72.5 years, subjects were assigned to control, strength training (ST) and power training (PT) groups for a period of 16 weeks. After 16 weeks, the Continuous Scale Physical Functional Performance (CS- PFP) test score for PT group was significantly higher than the ST group but ST had a higher maximal strength. No difference in peak anaerobic power was found. CS-PFP is a measure of physical functional ability which requires the performance of fifteen, real non-stimulated tasks, categorized into three groups based on effort as Low, Medium and Hard of which examples are (putting ona shirt), (Sweeping the floor), (climbing stairs) respectively.
Tests of functionality have not been limited to just a comparison between power and strength training. Functionality defined as competent ability to perform ADL was studied by Maria Fernanda et al. 2013. They measured levels of physical fitness and functionality increase with resistance training and aerobics in sedentary sixty-year-old adults. The study concluded that both resistance training and aerobic activity resulted in improvement of functionality.
Muscle strength which peaks in the third decade of life shows a gradual decline till 50 years of age, beyond which the strength loss is 15% per decade (Karsten Keller et al.2013). Limited number of longitudinal studies have been done about change in strength with ageing. Researchers (Bret Goodpaster et al. 2006) found a decline in
muscle strength which was much sharper than the corresponding muscle mass loss in a mixed group of 70-79 years aged adults in a three-year study. Loss of muscle mass alone was not sufficient to explain the decline in strength hence they hypothesized that it is not just the quantity but also the quality of muscle loss which ultimately decides strength loss in old age.
CAUSES OF MUSCLE STRENGTH AND POWER LOSS
Sarcopenia is the degenerative loss of skeletal muscle mass (0.5–1% loss per year after the age of 50), quality, and strength associated with aging. The drop is exponential and showed more pronounced changes in longitudinal studies compared to cross sectional studies (Walter R. Frontera et al. 2000). There are no available pharmaceutical treatments for this condition (Stuart M Phillips 2015).
The reduction in muscle strength has been attributed to the reduction in number and size of muscle tissues in older adults. In other words, reduction in cross sectional area of the muscle tissue. The losses are both in slow twitch and fast twitch fibers with a more pronounced reduction in the Type II fast twitch fiber types and the corresponding motor units (Joseph F Signorile 2007). Quantitative analysis of samples obtained through biopsy or autopsy has been carried out by investigators. Comparison of biopsy samples of older and younger individuals have revealed a reduction in cross sectional area of total number of muscle fibers and a significant relative reduction in the Type II fiber area with age (William J. Evans et al.
REDUCTION IN CONTRACTILE SPEED
Motor neurons and their associated muscle fibers defined as a motor unit are responsible for the contractility properties of muscle fibers. It is well established that older people have slower neuromuscular contractile properties (Martin R. Roos et al. 1997) hence leading to reduced contractile strength (T. J. Doherty et al. 1993). thereby reducing power production in ageing adults.
Human tendons connect muscle to bone and are responsible for transmission of force. Tendons have elastic properties which enable them to modulate force during locomotion (Wikipedia). Older tendons are more compliant then younger ones and take longer time to stretch, which makes them slower to transmit forces from muscle to bone. This points to the fact that older adults would take longer to contract their muscles and to effectively react to a situation which could lead to a fall (Narici et al. 2006)
Lower concentrations of some hormones, including growth hormone, testosterone, and insulin-like growth factor contribute to muscle atrophy. (Carol DerSarkissian
MUSCLE PROTEIN SYNTHESIS
Muscle Protein Synthesis (MPS) in human body is a continuous process of anabolic (synthesis) and catabolic (breakdown) processes. The balance of the synthesis and breakdown determines the net muscle protein in the body (Holloszy John O. et al. 1995). Reduced muscle mass is a result of decreased amount of muscle protein. The cause of reduced muscle mass in old age has more to do with a reduction is synthesis (Vandervoort et al. 2001) rather than breakdown. Reduced muscle synthesis in the aged will result in decrease in muscle mass. Also the ability of muscles to regenerate after an injury or overload is reduced with advancing age. Chantal Vella et al. 2002 have attributed a probable cause for this to decrease in population of satellite cells which are important functionaries for development of new muscle tissue. However, a study by Stephen M. Roth et al. 2000 did not find substantial dissimilarity in satellite cell population between the aged and the young. They however found morphological differences in the cells which pointed to less metabolic activity in cells of the old.
LEVEL OF PHYSICAL ACTIVITY
Sarcopenia cannot be attributed to muscle disuse, since it is observed that even highly competitive sportsmen also show decline. Reduced levels of physical activity cause a decrease in the muscle fiber size and not in its numbers as in ageing. However, it is possible that inadequate amount of appropriate resistance training would cause reduced recruitment of fast twitch muscle fibers, which may in time lead to their atrophy (Chantal Vella, et al. 2002).
STUDY METHODS AND FINDINGS EFFECT OF RESISTANCE TRAINING
ON ENERGY EXPENDITURE IN OLDER ADULTS
The purpose of a study by Hunter, Gary R., et al. 2000 was to evaluate the effect of resistance training on various levels of energy expenditures of older adults. The 26 weeks study in a mixed group of 61-72 years old adults measured REE (Resting Energy Expenditure), TEE (Total Energy Expenditure) AEE (Activity Related Energy Expenditure) RER (Respiratory Exchange Ration) and ARTE (Activity Related Time Equivalent). ARTE is an indication of free living physical activity in minutes per day before and after 26 weeks of training. TEE was measured pre-and post-training using the DWL (Doubly labeled Water) technique whereas REE was estimated through Calorimetry test between 5 am and 8 am, post training after 96 hours of conclusion of last training session. The level of VO2 and VCO2 were measured and the values used in calculating energy expenditure and RER. In addition, three standardized tasks which are typical of activities of free living older adults (Level walking, stair climbing and level walking carrying a loaded box) were conducted and VO2 and VCO2 measured. The amount of O2 consumption was converted to equivalent Average Energy Cost (AEC) of the three tasks by assuming a specific consumption rate of O2 per minute, into kJ/min. AEE (KJ/day) was calculated by first adjusting TEE for the thermic effect of food and then subtracting REE from it. Free living physical activity index (ARTE) in minutes per day was calculated as ARTE = AEE(kJ/day)/ AEC(kJ/Min). In addition to this Body Composition measurements were done pre and post training by Four Compartment Model (Estimation of body fat by BOD-POD Air displacement, Body Water by isotope dilution method and Bone Minerals by DEXA scan, Unmeasured quantity of body fraction made up of protein and glycogen) to ascertain the effect of training on FFM (Fat Free Mass) and Lipid Oxidation. (see Appendix for details of The Four Compartment Body Composition Model)
The results immediately showed reduction in RER, signaling improved fat oxidation concurrently with increase of TEE and REE. Fat Mass decreased and FFM increased. ARTE increased significantly (see Appendix for details on RER).
EFFECT OF INTENSITY OF STRENGTH TRAINING ON TRAINING
AND DETRAINING ADAPTATIONS IN OLDER ADULTS
Beneficial effects of strength training for older adults is well-established but how does the aged body respond to intensity of muscular stimulus? To get some insight into this question it would be pertinent to study the work of Fatouros et al. 2005 dealing with effect of exercise intensity on (a) Strength, (b) Anaerobic Power and (c) Mobility in older adults. The study was conducted on a group of 52 previously untrained older men (average age 71 years) divided into two groups, one following a Low Intensity Strength Training program (LIST: 55% of 1
RM) and the other following a High Intensity
Strength Training program (HIST: 85% of 1
RM) for a period of 24 weeks followed by a
48-week detraining period. For both groups, a whole-body training schedule was followed. Upper Body Strength (UBS), Lower Body Strength (LBS), Anaerobic Power (Wingate Test) Mobility (TUG – Timed Up and Go) were measured at the beginning, immediately after conclusion of the 24 week program and during detraining (16, 24 and 48 week). Vo2Max, subcutaneous skinfold thickness as an indicator of body fat (at seven points) were measured. The relation between thigh circumference and thigh skinfold measurements were used for estimation of change in muscle mass. The LIST and HIST groups performed 14-16 reps at 55% of 1RM and 6-8 reps at 85% of 1RM respectively. The 1RM values were checked every four weeks to adjust weights accordingly. Both groups also performed similar levels of abdominal crunches and back extension exercises. After completion of 24 weeks, participants were instructed to desist from any systematic exercise for next 48 weeks.
Findings: Both HIST and LIST showed decrease in body weight, with HIST showing the higher percentage decrease and the trend
was similar for sum of skinfolds (body fat estimation) and thigh skinfold. LIST could maintain this up to four months from completion of training whereas the figure for HIST group with same criteria was eight months. Thigh circumference (indicator of muscle mass addition) which had increased for both groups (more for HIST) at training were maintained by both up to 32 weeks. The LIST group lost whatever UBS it has gained within eight months whereas the HIST group maintained it throughout. LBS in LIST declined soon after four months and almost returned to pre-training values within eight months. HIST also showed declining LBS but it continued to be higher than baseline figures at the end of detraining. Anaerobic Power (AP) increased in both but to a greater degree in HIST. ST improved performance in TUG, Walking Ability, Stepping Up and Down tests with higher improvements in HIST. Hence in every aspect of the study HIST was found to be superior including anaerobic power, a finding which was in contrast to earlier study findings inferring ST to be ineffective in increasing AP.
STRENGTH TRAINING VS POWER TRAINING
Profiling the first of two studies; the first by Michael Drey et al. 2011, found no appreciable difference between strength training and power training, although both improved physical performance. However, the dropout rate in power training (relate to training) was higher than in strength training. Another interesting aspect of the study was implementation of Vitamin D3 supplementation for eight weeks in both groups prior to commencement of training program. The study was conducted on 69 mixed sex older adults in the age group of 65-
90 years split into two groups Strength Training (ST) and Power Training (PT) who underwent a training program of 12 weeks. Prior to starting training both groups were orally supplemented with Vitamin D3 according to the subject’s existing serum levels. The primary outcome of the study was SPPF (Short Physical Performance Battery) test. Secondary outcomes included measurement of Muscle Power (STS Power or Sit to Stand Transfer Power), aLM (appendicular Lean Mass) and the Short Form of Late Life Function and Disability Instrument (SF-LLFDI) a self-report measure of functionality. Both groups followed the same training protocol of warm up and balance exercises. Thereafter they followed the same routine of chest press, hip extension/flexion while standing, hip adduction/abduction while standing, tip-toe raises and chair rise. While the ST group performed the concentric and eccentric movements with the same average speed, the PT group performed the concentric movement with as rapid a pace as they could and a slower eccentric movement with same speed as ST group.
The first observation made was the rise in 25- OH-D3 serum level which had gone up substantially after eight weeks of supplementation. While the SPPB score did not change much, the Muscle Power score increased substantially before the start of the training program. The study elsewhere says even a one-point rise in SPPB is considered very significant as it increased the 5-year mortality rate significantly, hence it is probably not observable in the after effects to Vitamin D3 supplementation. SPPB scores did show improvement in physical performance after the 12 weeks training intervention however it was similar between ST and PT groups. Similarly, muscle power increase due to the intervention showed no change between the two groups neither did aLM values. Hence it was concluded PT could not be inferred to have higher benefit on physical performance than ST, but ST may still be preferred because of lower dropout rate to training program, also thehigh instances of Vitamin D3 deficiency and performance improvement after supplementation should be kept in mind, for future study approaches.
A contrasting study by Mizko et al. 2003 previously mentioned in this article needs elaboration. Like the study discussed in the preceding paragraph, the efficacy of strength training as compared to power training in improvement of Activities of Daily Living (ADL) such as stair climbing object lifting etc. have been investigated in this study. A mixed group of 39 elderly adults with average age 72.5 were similarly divided into Strength Training (ST), Power Training (PT) and Control groups. The ST group followed workouts for all muscle groups. The intensity was increased during the first eight weeks up- to 70% of 1RM and then remained at 80% of
1RM from weeks 9-16. The 1RM was adjusted every 4 weeks to account for increase in strength. The PT group followed the same protocol except, they performed jump squats instead of normal squats, which was being followed by the ST group. This was done for the first eight weeks to establish a strength base to incorporate power training for next eight weeks. After 8 weeks, they performed same exercises with reduced weight (40% of 1 RM) but at a higher concentric and eccentric velocity (with time of 1 sec and 2 sec respectively). Body fat was estimated using skinfold measurement, Lean thigh volume (LTV) was also estimated. The Continuous Scale Physical Functional Performance (CS-PFP) (see Appendix for details on CS-PFP) test was used as a measure of functionality. Maximal Strength was measured using the 1RM of chest press and anaerobic power was measured using the Wingate Test (see Appendix for detail on Wingate Test). Out of initial fifty participants 11 dropped out for various reasons. There were no appreciable physical differences between the groups at baseline. The CS-PFP score of the PT group was significantly higher than both the ST and Control group, but the study failed to turn up any significant difference between the two groups in maximal strength or Peak Anaerobic Power. Even though the PT group performed lesser absolute total work (due to the reduced load during weeks 9-16) as compared to ST group, the CS-PFP value in the PT group increased more than the ST group. This indicated the involvement of velocity of movement to be playing a role in physical performance improvement. The study concluded that PT, even though it required less work elicited a higher level of physical functionality compared to ST, and maximal strength and anaerobic power similar to a ST protocol.
The findings of Mizko et al. 2003 are in line with several other studies which emphasize that although resistance training has a positive effect on strength, when it comes to activities of daily living the strength increase does not necessarily mean improvement (Tom Hazell et al. 2007). Hence the studies involving power training need a more detailed look. However, before we go further into that, we look at two important factors which could play a crucial role in age related muscle and power loss. nutritional supplementation in conjunction with resistance training and effect of different training intensities on muscle protein synthesis in the aged.
EFFECT OF NUTRITION AND STRENGTH TRAINING INTENSITY ON MYOFIBRILLAR PROTEIN SYNTHESIS (MPS)
The onset of Sarcopenia consisting of decline in muscle mass (Myopenia) and decline in muscle strength (Dynapenia) can undermine a senior’s ability to perform activities of daily living (ADL) and increase injury risks due to disability and accidents. There is no known cure for this but it is well known that resistance training helps to arrest this
condition. However, the combined effect of resistance training with nutritional enhancements is hitherto unexplored but thought to hold great possibility for further increase in efficacy of resistance training. One would intuitively think that protein would be a key macronutrient which would play a very critical part in the whole equation. A study by Yifan Yang et al. 2011, investigated the effect of graded doses of whey protein isolate on Myofibrillar Protein Synthesis (MPS) in older men, coupled with and without resistance training. Hitherto studies conducted have shown a weaker response in comparison to younger adults. to protein intake and resistance training in older adults. They hypothesized that Leucine a key MPS regulator needs to be raised above a threshold level to stimulate MPS in the elderly, and there seemed to lie the possibility of the threshold being lowered with resistance training. Hence the study centered around a dose response of MPS to graded protein ingestion. Thirty-seven older men with mean age 71 were divided into four groups. Study revolved around ingestion of four different quantities of whey isolate protein followed by a unilateral exercise model so that each participant also served as control. Body mass, body composition, physical performance, various health parameters and evaluation of unilateral
10RM were evaluated one week before trial. Two days before trial commencement, participants received pre-packaged food in accordance with each person’s energy requirement and activity level as per Harris Benedict Equation and body mass was monitored to ensure energy balance. On day of infusion protocol at first the baseline blood and breath samples were obtained followed by a unilateral leg extension exercise based on each participant’s 10RM. Immediately after this blood and breath samples were again obtained followed by infusion of Leucine and Phenylalanine isotope as tracers. This continued for the four-hour duration of the test. Also immediately after obtaining post exercise blood and breath samples, participants in the four groups (W0), (W10), (W20) and (W40) were made to consume a drink containing 0, 10, 20 and 40 grams of Whey Isolate respectively. The drinks were enriched with leucine and phenylalanine tracer isotopes based on the amino acid levels in the isolate to maintain homogeneity between the infused isotope and the level of amino acids in the drink. Steady state was confirmed and leucine oxidation measured during the four-hour infusion by breath and blood samples. Muscle samples were obtained from both legs’ vastus lateralis. Fractional Synthetic Rate (FSR) (see Appendix for details on FSR) was calculated by taking the difference in protein bound enrichment between the biopsy sample and the base line plasma protein level, by obtaining the average phenylalanine enrichment between the two leg biopsies after completion of infusion (240 minutes).
Plasma insulin was similar in all four groups at 0,3, and 4 hours post drink, but rose at one- hour mark, maximum for W40 followed by W20 and W10. At the two-hour mark, W20 declined to be at the same level as W0 and W10 while W40 continued to be higher than W0 and W10. Hence insulin remain at high levels longer with 40 grams Whey Isolate dose. Also, the plasma level of the isotope was stable from 20 minutes to 240 minutes. No difference in IC phenylalanine was found intra group or between exercised and non- exercised legs. Leucine oxidation was found to be highest in W40 group. Myofibrillar FSR in exercised leg had increased significantly for both W20 and W40 with not much difference between the two. The ratio was greater in exercised leg as compared to non- exercised legs for all groups with W40 having an increase of 32% over W20. Thus, the study showed that a dose of 20 grams is enough at Basel rate to cause MPS and higher
dosage of 40 grams did not cause any appreciable increase. However, when coupled with resistance training, 40 grams of whey which did not increase MPS any more than a 20 grams dose in basal state, increased MPS by more than any other dosage. Thus, it was shown that older adults can respond to a higher dose of protein coupled with resistance training as compared to younger adults, which other studies had shown to respond to much lower dose of 20 grams of protein.
Having shown the correlation between nutrition (protein) and MPS let us look at another study which deals with the dose- effect relationship between resistance exercise and Myofibrillar Protein Synthesis (MPS). A study by Vinod Kumar et al.
2009, studied the effect of varying training intensities on MPS between two group, one of healthy young men , average age 24 and the other of older men average age 70, the subjects per group being 25. The study hypothesized that a) different training intensities would have a does dependent relation with anabolic signaling molecule phosphorylation and MPS, b) the relation would be linear up-to 60% of 1 RM value, c) there would be no MPS before one hour post workout, d) The effect would be more pronounced in younger men.
The groups were identical in physical and overall health, absence of insulin resistance, body mass indices, lean body mass, and right and left leg lean masses. The only difference was in the unilateral 1 RM strength in leg extension exercise. Each subject’s dominant leg 1RM was measured as was body composition.
The tests were conducted in fasted state (overnight fasting), with the participants in the beginning being infused a L-Leucine isotope tracer continuously for seven hours. Test samples included venous blood sampling every half hour, Biopsies of rest
and exercise leg as follows: a) Rest Leg biopsies just before starting infusion and after2.5 hours, b) Exercise leg biopsies at 3 h approx. (just after exercise), 4.5 h and 5.5 h.
Exercise started with leg extension exercise with dominant leg 2.5 h after start of infusion, in groups of five at randomly assigned intensities between 20% to 90% of subjects 1RM. The number of repetitions was adjusted as per intensity to keep the volume of work approximately same (e.g. 20% x 3 x 27 is approx. equal to 40% x 3 x 14). Time under tension was kept at 4 seconds
Determination of study variables was done as follows: Myofibrillar protein was isolated and FSR was determined from levels of leucine isotope tracer between biopsies. Phosphorylation of p70s6K and 4EBP1 was measured using with anti-phosphoantibodies.
Data analysis showed a dose-response relationship between MPS and resistance exercise for both groups. When measured 1-
2h post exercise it showed a sigmoidal relationship with intensities with lower increase for lower intensities and much greater increases for intensities from 60% to
90% of 1RM ( 5% of 1 RM showing the highest increase). However, the difference between groups was significant younger men achieving 30% higher MPS. MPS fell to Basel values within 2-4 hours of exercise. The younger adults showed a sharper response to phosphorylation of p70s6K and
4EBP1 at 60–90% remained 1 RM as compared men. The data clearly showed that
MPS was dose response dependent with a plateau forming between 60% to 90% of
1RM and that older men exhibited blunted response to anabolic signaling and MPS when subjected to resistance exercises.
POWER TRAINING STUDIES AND STRATEGIES
Development of strategies to cope with decrease in muscle power with age should be
the focus of any exercise program for the old. For activities of daily living, depends on the individual’s ability to generate force rapidly which is a critical component of ambulation (Evans 2000). Hence programs directed towards the elderly should ideally include schedules for rapid force generating exercises. This would help in preservation of age relate loss of muscle power, increase independence in activities of daily living (ADL) and substantially reduce risks of accidents in the elderly. With this backdrop, we look at several studies dealing with Muscle Power and Power Training for the aged.
STUDIES DEALING WITH SPEED AND LOAD IN POWER TRAINING:
Power (P) is nothing but the product of Force (F) and Velocity(V). P = F x V. The impact of High Velocity training as opposed to low velocity training which is more common was studied by Roger A. Fielding, 2002. The study was conducted exclusively on women, with a sample group size of 30, and average age 73. The subjects were further sub-divided into two groups which underwent a 16 weeks High Velocity Resistance Training (HI) and Low Velocity Resistance Training (LO) respectively. The exercises performed were exclusively of lower body, namely Leg Press (LP) and Knee Extension (KE). Measurements were made of 1RM and Peak Power for both exercises. 1RM of the two exercises were determined at baseline and thereafter after every two weeks and exercise intensity adjusted every time. Peak Power was also measured at baseline and thereafter every two weeks. Peak Power was assessed at intensities ranging from 40% to 90% of
1RM. At each intensity setting a software calculated the power and work done for that setting. The highest power achieved was recorded as peak power.
Exercises were performed at 70% of 1 RM throughout the training. The HI group
followed a pattern of Concentric: As fast as Possible, Maintain Extension: 1 second, and Eccentric: 2 seconds. The LO group followed the same exercise protocol except that the concentric part was completed in 2 seconds. After each set the average power and total work done were calculated and recorded for each group to compare the training intensities between both groups. It was seen that intensity was being maintained at nearly desired level of 70% of 1RM and even total work done was the same in both groups. However as desired substantially more power was being generated in HI group.
No difference in Muscle Strength was observed between groups at baseline and observations for LP and KE for both groups did not show any difference of statistical significance (was same). Peak power happened at 75% for both HI and LO groups and were the same at baseline. Peak muscle power increased significantly for both HI and LO groups. For LP it increased substantially more for HI and faster (at four weeks) as compared to LO (after 8 weeks). Improvements in KE peak Power was not significantly different within the groups. To separate out the effect of Muscle Strength from Peak Power, regression analysis was done for both groups combined at baseline and after 16 weeks intervention. In both readings for LP and KE substantial contribution was found of 1RM strength to variance in peak power, however studying the groups data separately after 16 weeks showed a different trend. In HI, for LP only24% of the variance was due to 1RM strength compared to 78% in LO. Similar trend for KE though lesser to a certain degree was observed for KE too. Hence the data clearly showed the increase in Leg extensor peak power because of training specifically designed to increase muscle power in older adults (women in this case). From the study: “Because of their increased perceived risk of falls and physical disability and because theyhave reduced absolute and relative lower extremity power, women with mild levels of self-reported functional limitations were exclusively targeted in this intervention study”.
But questions remain involving the power equation Power (P) = Force (F) x Velocity (V). Are there any optimal velocity and load when talking about power training parameters for older adults, if yes then what are they. Nathan J de Vos et al. 2005 investigated the effect of different loads in their study by assigning adults with mean age of 69, sample group size 112, into four sub- groups depending on explosive resistance training (RT) carried out as a percentage of their 1RM or control. The groups were20%(G20), 50%(G50), 80%(G80) and non- training control (CON). All groups except CON were imparted 8-12 weeks of training based on their 1RM value. The exercises, five in numbers consisted of a fast-concentric phase and a slow-eccentric phase. At the time of study there existed trainingrecommendations for slower reps at 60-80% of IRM and explosive training at 40%-60% of 1 RM for older adults but no study for optimal training intensity for explosive RT existed. The study hypothesized that explosive RT using heavy loads (80% of1RM) would help in delivering more power than at range of 20%-50%. The study participants were not aware of this. All testing parameters, fasting body weight, body fat % and fat free mass were taken before the random allocation of participants to different
groups, and after 8 and 12 weeks respectively. In addition, 1RM strength and full range of motion with a minimally loaded set were measured. 1RM was also measured weekly. Peak muscle power was measured 30 minutes after measurement of 1RM at ten different intensities (20%, 40%, 50%, 55%,60%, 65%, 70%, 75%, 80% and 85%) of1RM with the concentric part being completed at the fastest possible speed and eccentric in a time of 3 seconds. Verbal cuing “GO” was used. Power was calculated between 5% and 90% of concentric movement. Work done was calculated using data generated from concentric movement. The highest mean power for the various loads was recorded as the peak power. Muscle endurance was tested by setting the load at 90 of baseline 1RM and then totaling the number of repetitions in each of the five exercises then dividing the same by five, for each of the participants.
Training Intervention was carried out in which the participants trained at one of the intensities (20%, 50% or 80% of 1 RM) according to the group allocated in. Training used the same exercises as in testing and loads were adjusted each week to account for change in 1RM. Training proceeded the same way as for power testing. Training was performed in mixed groups of maximum five participants barring members of control group who did not participate but were asked to maintain a certain level of activity throughout the study period.
The training intervention caused significant rise in absolute peak power, with reference to control, and relative to each other. Similar was the trend in muscle power. Both changes in average peak power and muscle strength were related to change in fat free mass. Muscle endurance measured as average number of repetitions also showed group wise increasing trend. Increase in endurance was also linked to training intensity. Thus, the study concluded that different training intensities produced similar increases in muscle power which was not the hypothesized outcome. Increase in muscle power in G50 was found to be like higher loads (G80) but greater than lighter loads (G20). The study found a dose response relationship of intensity with muscle strength and endurance. Hence peak power, strengthand local muscle endurance would all play a part in late life functional independence.
POWER TRAINING AND POSTURAL BALANCE
Maintaining balance while performing simple daily tasks has been identified as a key factor in prevention of fall in older adults. Of the strategies present, walking, strength training, balance specific exercises have given limited benefits. Muscle power and velocity of movements have shown to have a link on functional tasks. Lower muscle power with declining age has also been reported to be linked to lower balancing ability thereby increasing the probability of fall. Postural stability requires fast response to destabilizing stimuli. However, the body’s ability to generate fast responses rapidly reduces with age. The study by Rhonda Orr et al. 2006, explored the effect of high velocity training at different intensities on improving postural balance. 112 adults, mean age of 69 years were divided randomly into three groups LOW HIGH and CON, for 12 weeks of power training at LOW ( 20% ), MED ( 50%), and HIGH (80%) of 1RM and a non-training control group CON. Training frequency was twice a week of three sets each of five exercises.
Balance was assessed on a computerized force platform. The system allowed measurement of two parameters; Body Sway and Single Leg Static Balance. Increased body sway is an indicator of reduced posture stability and associated fall risk. The other parameter, static balance, timed with and without vision input was also a marker of balance deficit and postural control resulting in instances of fall.
Three trials for each of the tests were allowed, without losing balance while performing the test. If the participants failed to complete even one of the trials in any test, the longest time till which it was performedwithout losing balance was measured and further used. The number of trials and losses of balance were also recorded.
Tests: Balance under three conditions: a) Narrow stance both legs on platform moving in forward and backward (anterior/posterior) direction at a specified speed. b) Same as a) but with the platform tilting up and down up to a specific angle in anterior/posterior direction. c) Timed preferred one leg stance on still platform, with eyes open and eyes closed. Time per test was 30 seconds. Total time of maintaining stance and maximum sway in anterior/posterior direction and mediolateral direction (side to side) were measured. There were 12 scores from the bilateral tests and six from the unilateral tests. Two scores were used 1) Balance Index (BI)
= Sum of 12 sway measures + (180- sum of six, time measures). Since lesser sway score means better balance the sum of time scores was subtracted from max time of 180 secs so that the lesser is better direction is maintained for overall BI score. 2) Loss of Balance Score which recorded the total number of times balance was lost. Lower score meant better balance.
Muscle strength and Power measurement: Muscle strength was obtained by adding the
1RM values of all the five tests. For peak power and velocity same equipment and exercises were used with intensities of 20%,40%, 50%, 55%, 60% 65%, 70%, 75%, 80%,85% of 1RM. The concentric part completed at the fastest possible speed and eccentric in a time of 3 seconds. Verbal cuing “GO” was used. Power was calculated between 5% and90% of concentric movement. Work done was calculated using data generated from concentric movement. The highest mean power for the various loads was recorded as the peak power. Total peak power was obtained as the sum of peak powers in all five exercises. Peak velocity was the highest recorded velocity between 5% and 90% of concentric movement at 20% of 1RM. Average peak velocity was the average obtained for all five exercises. Muscle endurance was tested by setting the load at 90 of baseline 1RM and then totaling the number of repetitions in each of the five exercises then dividing the same by five, for each of the participants to get average endurance. For body composition 12 hours fasting fat free mass was determined by bioelectrical impedance method. Power training Intervention consisted of the participants performing explosive Resistance Training (RT) at one of three intensities; 20% (LOW),50% (MED), 80% (HIGH). Same five exercises, twice a week was conducted for 10 weeks with resistance being adjusted according to most recent 1RM. Power training intervention caused significant improvement in BI. With the LOW group showing significantly more improvement over HIGH MED and CON. Total loss of balance scores also improved with LOW repeating the same trend as in BI. Of baseline characteristics of Age, FFM, Lower Peak Power and Lower Average Peak Velocity, the last one showed a predictive characteristic of post training balance improvement.
Power training at high velocities is known to improve peak power production and is identified as one of the areas to focus on for training for functional independence in older adults. The ability to produce power at low external resistance at high velocities is a key aspect related to safely. High speed power production can be called upon at any time such as in instances of losing balance due to fall or while trying to apply brakes in a motor vehicle to suddenly make it stop (Stephen P. Sayers, et al. 2014).
POWER TRAINING AND BRAKING ABILITY
Effect of high speed power training on muscle performance and braking ability was studied by (Stephen P. Sayers et al. 2012) in a mixed group control study of 72 older adults of average age of 72 who were divided in three groups, High Speed Power Training (HSPT), Slow Speed Strength Training (SSST) and Control (CON). Resistance training was imparted for 12 weeks three times a week with the HSPT group performing exercises at 40% of 1 RM, doing the concentric movement at explosive high speed and the eccentric in 2-3 seconds. The SSPT group followed the same protocol except for performing the exercises at 80% of 1RM and performing concentric and eccentric movements, both in 2-3 seconds each. The main outcome measure included muscle performance (1RM), muscle power at different percentages of 1RM and velocity and force at peak power. After measuring
1RM with progressively increasing resistance, peak muscle power was obtained at various external resistances ranging from40% to 90% of 1RM. The maximum velocity and force were obtained at each resistance setting. 1RM was reset every two weeks in HSPT and SSST groups. However, posttraining muscle performances were measured with loads relative to original 1RM to reflect real world situation where resistances do not change with the subjects getting stronger.
The second test included measurement of braking speed using an automobile simulator to find out if any training induced improvement in speed and power improved any functional performance. Participants were observed and found to be using the hip knee and ankle joints to slam on brakes in emergency situations, hence the participants were asked to use the same approach in braking during the response testing process. Also, this movement closely matched the leg press exercise participants had done during strengthening, the other being knee extension. Two events were recorded. The initial reaction time to simulator red light, that is the time taken to initiate movement to lift foot of accelerator after seeing the light and second, the braking time, which was the time taken to take the foot of the accelerator and to the brake.
The third measure was ratings of perceived exertions (RPE) to explore the effect of different training protocols on participants and was done using the Borg Scale (see Appendix for details on Borg Scale). The study which started with baseline figures showing no difference between HSPT, SSST and CON showed marked differences post training on loads relative to baseline. While HSPT group members increased their muscle peak power and the peak power velocity across the entire range of external resistances tested over CON, the SSST group showed improvement only in 70%-90% resistance range for the same parameters. Hence HSPT was found to be more effective in improving power and speed across a wide range of real world external resistances as compared to SSST.
Similarly, in the driving simulator test (see Appendix for pictures of driving simulator), while there was no difference at baseline, significant differences emerged within the groups post training. While there was no difference in reaction time there were significant difference in braking time. While HSPT improved over 15% over baseline figures, it was only 2.6% for SSST.
RPE ratings for both leg press and knee extension had differences in HSPT and SSST. While Leg Press ratings were “Light to Somewhat Hard” for HSPT, it was “Somewhat hard to Hard” for SSST. Knee Extension for HSPT “Somewhat Hard to Hard” for HSPT and “Hard to Very Hard for SSST”. Hence despite similar workloads, HSPT was perceived to be easier.
DEALING WITH AGE RELATED STRENGTH AND POWER LOSS
Sarcopenia is a gradual loss of skeletal muscle which takes place in human bodies with increase in age. Even though there may be loss in muscle tissue after thirty, the rate of muscle loss accelerates faster after fifty years of age. The onset of sarcopenia is characterized by two main factors. The first is loss of strength, which translates into loss of ability to handle or lift heavy objects or in moving heavy external resistances, like opening a heavy iron gate or door or lifting and carrying a large chair. It can even mean not being able to lift one’s own weight, be it a simple task like getting up from a chair or being able to climb a short flight of stairs. The other loss is of muscle power, which means not being able to react or move quickly with speed as per requirements of external real- world situations. This could mean a simple act of crossing a busy road or slamming brakes of a car to avoid a collision, preventing a fall if one stumbles or even reacting to a high velocity object travelling one’s way.
It is important to differentiate between these two aspects of loss. While one is to do purely with strength the other has more to do with power. While strength can be called the force, which is required to overcome an external resistance, Power is the ability to do so at a given speed. So, Power (P) = Force (F) x (V) Velocity. Hence to be able to live a sustainable independent life both components of muscle response i.e. strength and power are important. Hence not only getting up from a chair is important but to get up and walk steps without falling is equally so. Being able to maintain one’s balance also becomes a critical factor, one which is dependent on the power component one has. However, it is important to note that all components are inter-related. One cannot have much power unless one is able to at least counter an external resistance with one’s strength. If one is not able to lift an object there will also be no ability in moving it, at any speed. Similarly, if one’s knee and hip extensors are so weak that one is not able to lift or bend one’s leg to apply the brakes, where is the question of being able to do that with speed? Hence, to have some minimum basic power one must have a foundation of strength. However, it is easy to see that development of strength itself will not be of much benefit in the elderly if there is no mobility improvement. A very well-built elder may still find it difficult to cross a road quickly or to jump over or avoid simple obstacles even though they have more strength.
Researchers have been quick to realize the importance of power training in elderly because of its practical applications and direct ability to influence an independent life, as it’s the power component which is called upon more often in dealing with the external world on a daily basis. One would not be probably expected to lift heavy weights when old but certainly one would expect and be expected to retain mobility, even at an advanced age. Why this becomes more important is because lack of power can cause injuries from falling. Falling is one of the major causes of concern in elderly which causes injuries that may take the elder a long time to heal and even longer to rehabilitate, as during the time an elder is recovering there is almost little or no exercise resulting in further loss of strength and power. Hence fall prevention is of utmost importance in older adults.
Researchers have found that power in elderly declines much faster than strength. This is because it is not just the muscle mass which reduces but also the type of muscle fibers. Type II muscle fibers which are also known as fast twitch fibers are the ones which reduce much faster than the slow twitch Type I fibers. Hence not only does strength go down but also power at a much higher rate. Also, muscles lose their capacity to grow and regenerate in older adults and even become less responsive to exercise and nutrition.
Strength and power improvements in older adults pose a separate challenge because most older adults become less active with age and inactivity causes the muscles to atrophy even more. It is not difficult to see the independence in daily living between an adult with varying level of activity and conscious engagement in everyday living, as compared a sedentary individual of the same age group.
It’s not just muscles which atrophy with age. The connecting tissue tendon, also plays a role. How? Tendons in older adults are more compliant (less elastic) than in younger adults. Hence force transmission to bones takes longer and as a result the reaction time to for muscle contraction is lot more than younger adults. This affects the older adults negatively in emergent situations which require fast response time.
ADVANTAGES OF STRENGTH AND POWER TRAINING
The advantages of strength and power training for older adults are numerous. Strength training increases daily energy consumption by increasing the activity level. If one was to discount the training related energy consumption, it still increased resting energy expenditure, probably due to increase in lean body mass which influences the resting metabolic rate. Strength training also has a positive effect on the fat burning process.
Strength training has positive effect on many components of fitness for older adults. It increases walking and stepping up and down ability, increases anaerobic power and lean body mass. The effect of strength training stays even when the subject stops training.
The higher the intensity the longer the effect stays. Hence it is possible for older adults to take training gaps which could be preplanned or maybe due to illness and get back to training at the earliest instance thereafter without losing much of the training effects of previous sessions.
OBSERVATIONS ON STUDY FINDINGS
It is to a certain extent expected that the diet and nutrition part in the life of old aged are not as importantly focused on as maybe younger adults of a family. Hence several seniors may suffer from nutritional deficiency such as lack of adequate proteins and vitamins in their meals. One study found a significant rise in strength with supplementation of Vitamin D3 pointing to large scale deficiency in Vitamin D3 in the sample population.
Another found a marked increase in myofibrillar protein synthesis when resistance training is nutritionally supplemented with protein, even though the protein requirement was more than one would require for a younger adult. Also, older adults showed a dose dependent response to muscle growth even though the response was less than for younger individuals.
Both these showed a possible effect of developing bluntness to exercise and nutrition. However, if one was to get past the initial stages and maintain an increased amount of structured nutrition (protein being the most important macronutrient) and if viable workout with loads around 75% of
1RM it is possible to get muscle synthesis even in older adults.
So far, the studies involving ST has shown substantial effectiveness in increasing daily living functionality with strength training protocol provided same is also supplemented with quantified structured nutrition.
However, many studies have found power training to have a clear edge over strength training as far as functionality goes and speed of movements in training did matter for better adaptations to daily activities. Strength did not translate to any major advantage in that adaptability. Hence while strength training had benefits, power training had clear advantages for older adults.
Therefore development of any fitness regime for older adults must specifically focus on efforts for generation of rapid movement speed, or explosive movement in the subjects. This is required as it significantly helps them mitigate problems of daily living such as walking, stepping up and down climbing, reaching up, balancing, driving etc., without posing a threat to themselves and to others.
Power training studies have been conducted on lower body parts which are engaged in movement and rightly so as the importance of possessing power is much more in lower part of the body as it controls various movements such as walking, turning, stepping up and down etc. Moreover, the upper part of the body, arms head torso etc. are more used hence chances of muscular atrophy in lower parts appear to be more. Therefore the choice of exercises i.e. Leg Press and Knee Extension seem to be appropriate for the studies. Most studies focus on a faster concentric movement (as fast as you can) and a slower eccentric movement for power training intervention while for comparison, strength training interventions are done with similar concentric and eccentric speeds. Studies which focused on one fixed external load for the different training protocols returned with the conclusion that the power training interventional protocol was more effective in increasing muscle power. Hence strength training by itself was not sufficient to meet functional requirements of older adults.
Other studies conducted tests on various external load settings and found that even different load settings produced increase in muscle power pointing to the fact that power training does not need to be done at excessively high load settings. Muscular strength and endurance however showed increase with increasing intensity. Hence training protocol for older adults could be made with a combination of both power and strength protocols.
A very important parameter of functional independence was established by a study which focused on the balance aspect. The ability to keep balance in horizontally and angularly moving surfaces and to keep single leg balance with and without visionary stimulus improved significantly with power training and more so with lower intensities.
Power training has shown improvement in muscle power and speed against a wide range of external resistances, improved functional requirements of slamming brakes to bring a vehicle to a halt and more importantly is perceived to be much easier to perform then strength trainings with similar workloads.
I followed three weeks of power training on self, which consisted of stationary jumping up and jumping down on a stationary platform, running long jump, and standing long jump. After doing just three sessions of this, I could take running jump (backing up two steps) on to pavements 2 feet high, something I could not do even after one year of strength training, during which time I had regularly trained lower limbs. Currently trying effectiveness on other family members, with ball slamming, Posture balancing, running long jumps, zig zag jumps, ball catching etc. However, I have faced mental barrier from subjects in using new found abilities when real life situations have arisen, probably because of the long mental conditioning to a lower ability that the subjects possess. Will need to encourage the subjects to be more active in using the improved functional abilities in real life situations, till mental barriers are resolved.
Power training is equally critical as strength training to ensure functional independence in older adults. Power training helps them to overcome diminished physical capability in performing activities of daily living. This training is more critical after the adult crosses the fifth decade, when strength and power starts to fail rapidly, power more than strength. Advancing age does not hamper the individual from getting benefits from strength and power training. While strength training should focus on whole body, power training should focus more on lower body as it determines functional capability and proves to be a useful tool in overcoming instances of falls or accidents, which cause grievous injuries to them and others. Power training gives effective results even at lower external loads with improvement in speed of movement, which is so essential to preserving explosive movements and balance in older adults. Training at different external resistances arms the individual to deal with a diverse range of situations in the real world. Training for improvement of postural balance on steady or unsteady surfaces should be an integral part of the training design. A base of strength training helps in getting better results along with power training. Proper nutrition and supplementation of micronutrients will help the efforts of the seniors to get involved in strength and power training.
A base of strength training will help the seniors get the best out of power training, hence training protocols must incorporate elements of both. Baseline testing needs to be done to ascertain existing strengths and power capabilities, before laying out exercise routines to prevent injuries and perceptions of training being hard. It has been observed that despite increase in ability there exists a mental barrier in using it in real life situations, therefore clients should be made aware of their new-found abilities and encourage them to use the same independently.
Till the client adapts to and implements the improvements in functional ability brought about by strength and power training elements, in the real world, the job of the trainer is not finished.
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30. Wikipedia link :
THE FOUR COMPARTMENT BODY COMPOSITION MODEL
A combination of methods which comprises of
1. Estimation of Body water: By isotope dilution method
2. Estimation of Body Fat by UWW (Under Water Weighing) or BOD POD (Air Displacement
Plethysmography). D(b) * 0.9 = density of fat
3. Estimation of Bone Mineral content by DEXA Scan
4. Unmeasured portion of body fraction consisting of protein and glycogen
Ref : (Hunter, Gary R et al. 2000)
RER (RESPIRATORY EXCHANGE RATIO)
The respiratory exchange ratio (RER) is the ratio between the amount of carbon dioxide (CO2) produced in metabolism and oxygen (O2) used. Humans typically inhale more molecules of oxygen than they exhale of carbon dioxide because air contains much more oxygen by volume. RER is about 0.8 at rest with a modern diet. The ratio is determined by comparing exhaled gases to room air. Measuring this ratio can be used for estimating the respiratory quotient (RQ), an indicator of which fuel (carbohydrate or fat) is being metabolized to supply the body with energy. This estimation is only valid if metabolism is in a steady state. Calculation of RER is commonly done in conjunction with exercise tests such as the VO2 Max Test and can be used as an indicator that the participants are nearing exhaustion and the limits of their cardio-respiratory system. An RER greater than or equal to 1.15 is often used as a secondary endpoint criterion of a VO2 Max Test. An RER of 0.70 indicates that fat is the predominant fuel source, RER of 0.85 suggests a mix of fat and carbohydrates, and a value of 1.00 or above is indicative of carbohydrate being the predominant fuel source (excerpted from wiki)
The Wingate test (also known as the Wingate Anaerobic Test (WAnT)) is an anaerobic test, most often performed on a cycle ergometer, that measures peak anaerobic power and anaerobic capacity. The test, which can also be performed on an arm crank ergometer, consists of a set time pedaling at maximum speed against a constant force. The prototype test based on the Cumming’s test was introduced in 1974, at the Wingate Institute and has undergone modifications as time has progressed. The Wingate test has also been used as a basis to design newer tests in the same vein, and others that use running as the exercise instead of cycling. Sprint interval testing such as is like the construction of the Wingate test has been shown to increase both aerobic and anaerobic performance……
Read more at https://en.wikipedia.org/wiki/Wingate_test
THE CONTINUOUS SCALE PHYSICAL FUNCTIONAL PERFORMANCE (CS- PFP)
The Continuous Scale Physical Functional Performance (CS-PFP), and its shorter version the Continuous Scale Physical Functional Performance — 10 (CS-PFP10), are valid, reliable, and sensitive measures of physical function. The CS-PFP and CS-PFP10 have good reliability and are sensitive to detecting change in function in populations with low (older adults living in assisted living) and high (adults living in the greater community) functional levels.
Read more at http://drelainecress.com/about-dr-elaine-cress/
See video for more details: https://www.youtube.com/watch?v=Y5taFjUPLV8
DERIVATION OF THE FORMULA FOR THE FSR
The fractional synthetic rate is defined as the rate of incorporation of a precursor into a product per unit of product mass. The usual formula to calculate this parameter from a stable isotope tracer experiment is
FSR = (initial rate of change in product enrichment)/initial precursor enrichment
This formula was first applied to experiments in which an amino acid was enriched with a stable isotope and infused as a precursor for the apolipoprotein of interest
Ref: Estimating the fractional synthetic rate of plasma apolipoproteins and lipids from stable isotope data ( David M. Foster,’.. P. Hugh R. Barrett: Gianna Toffolo,t William F. Beltz, and Claudio Cobellit ) Journal of Lipid Research Volume 34, 1993
Read more at …… http://www.jlr.org/content/34/12/2193.full.pdf+html
RATING OF PERCEIVED EXERTION USING BORG SCALE
In sports and particularly exercise testing, the rating of perceived exertion (RPE), as measured by the Borg rating of perceived exertion scale (RPE scale), is a frequently used quantitative measure of perceived exertion during physical activity. In medicine this is used to document the patient’s exertion during a test, and sports coaches use the scale to assess the intensity of training and competition.
THE BORG SCALE OF PERCEIVED EXERTION
One way to gauge how hard you are exercising is to use the Borg Scale of Perceived Exertion. The Borg Scale considers your fitness level: It matches how hard you feel you are working with numbers from 6 to 20; thus, it is a “relative” scale. The scale starts with “no feeling of exertion,” which rates a 6, and ends with “very, very hard,” which rates a
Driving Simulator Used by (Stephen P. Sayers and Kyle Gibson 2012)
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