Of all the physiological changes that occur during the aging process, among the most important with regard to quality of life and functional independence are declines in muscle strength and peak oxygen consumption (peak VO2). Numerous cross-sectional studies have demonstrated a decline in peak VO2 of 5% to 10% per decade in untrained individuals. Although age per se is thought to contribute to this decline, age-associated decreases in vigorous physical activity and muscle mass exacerbate the process.
Fleg, L.J. et al. Accelarated Longitudinal Decline of Aerobic Capacity in Healthy Older Adults. Circulation, American Heart Association, 2005; 112:674-682.
The ability of older person to function independently in the community depends largely on maintenance of sufficient aerobic capacity and muscle strength to perform daily activities. The perceived degree of effort and breathlessness of a given activity is determined by its oxygen cost relative to a personís peak VO2. Tasks perceived as requiring substantial effort in deconditioned individuals tend to be avoided, setting off a vicious cycle of further reduction in aerobic capacity, causing further avoidance of physical activity and further loss of muscle mass and strength.
Fried L.P. et al. Frailty in older adults: evidence for a phenotype. J Gerontol A:Med Sci. 2001; 56A:M146-M156.
Benefits of weight training to some age-related physiological changes:
Background: While its aetiology is poorly understood, the multifactorial sequelae of sarcopenia are well documented and present a major public health concern to our aging population, as both the quality of life and the likelihood of age-associated declines in health status are influenced.
Strength and muscle mass are increased following resistance training in older adults. Muscle quality (strength relative to muscle mass) also increases with resistance training in older adults possibly for a number of reasons, including increased ability to neurally activate motor units and increased high-energy phosphate availability. Resistance training in older adults also increases power, reduces the difficulty of performing daily tasks, enhances energy expenditure and body composition, and promotes participation in spontaneous physical activity.
Hunter G.R. et al. Effects of resistance training in older adults. Sports Med. 2004;34(5):329-48.
Strength training is known to be an effective means of increasing muscular strength and size in many populations, and can be utilized successfully to significantly improve muscle strength, muscle mass and functional mobility in elderly women up to the age of 96 years.
Foster-Burns SB. Sarcopenia and decreased muscle strength in the elderly woman: resistance training as a safe and effective intervention. J Women Aging. 1999; 11(4):75-85.
Many consequences of sarcopenia are preventable or even reversible. Progressive resistance exercise can produce substantial increases in strength and muscle size, even in the oldest old. For many older patients, weight training represents the safest, least expensive means to lose body fat, decrease blood pressure, improving glucose tolerance and maintain long-term independence.
Evans, W.J. Reversing sarcopenia: how weight training can build strength and vitality. Geriatrics. 1996 May; 51(5):46-7, 51-3.
Strength training increases muscle strength and muscular power in the elderly thus counteracting part of the age-related effects. The benefit of strength training is greatest in frail elderly and the oldest old, although elderly in general will benefit from strength training.
Jespersen, J. et al. Sarcopenia and strength training. Age-related changes: effect of strength training. 2003 Aug; 165(35):3307-11.
The evidence presented suggests that strength training is an effective intervention for improving strength, muscle mass and muscle quality and delaying the onset of physical disability in the elderly.
Roth, S.M. et al. Strength training for the prevention and treatment of sarcopenia. J Nutr Health Aging. 2000;4(3):143-55.
High intensity resistance training (HIRT) has led to increased protein synthesis, along with muscle hypertrophy measured at the whole body, whole muscle, and muscle fibre levels, in older adults. Typically, the strength increments associated with HIRT have been much larger than the hypertrophic response.
Porter, M.M. The effects of strength training on sarcopenia. Can J Appl Physiol. 2001 Feb;26(1):123-41.
The results seem to suggest that strength training can counteract the age-related changes in function and morphology of the ageing human skeletal muscle.
Klitgaard H. et al. Function, morphology and protein expression of ageing skeletal muscle: a cross-sectional study of elderly men with different training backgrounds. Acta Physiol Scand. 1990 Sep;140(1):41-54.
In conclusion, there is no other group in our society that can benefit more from regularly performed exercise than the elderly. While both aerobic and strength conditioning are highly recommended, only strength training can stop or reverse sarcopenia. Increased muscle strength and mass in the elderly can be the first step toward a lifetime of increased physical activity and a realistic strategy for maintaining functional status and independence.
A 6-month resistance training program increases muscle mass and improves Bone Mineral Density (BMD) of the femoral region in young and healthy older men and women, for a trend for this to be greater in the young subjects.
Ryan A.S. et al. Regional Bone Mineral Density after resistive training in the young and older men and women. Scand J Med Sci Sports. 2004 Feb;14(1):16-23.
Effective alternatives to hormone replacement therapy are available using resistance training exercise and supplementation with calcium and vitamin D to ameliorate bone loss and promote new bone formation.
Benton M.J. & White A. Osteoporosis: recommendations for resistance exercise and supplementation with calcium and vitamin D to promote bone health. J Community Health Nurs. 2006. 23(4):201-11.
This data indicate high-intensity resistance exercise training was successful for improving BMD of the femoral neck in healthy elderly subjects. Also, these data suggest that high-intensity resistance exercise increased bone turnover, which over time may lead to further changes in BMD.
Vincent K.R. & Braith R.W. Resistance exercise and bone turnover in elderly men and women. Med Sci Sports Exerc. 2002 Jan;34(1):17-23.
GENERAL HEALTH AND PERFORMANCE :
Resistance training has been shown to reduce body fat, increase basal metabolic rate, decrease blood pressure and the cardiovascular demands to exercise, improve blood lipid profiles, glucose tolerance, and insulin sensitivity, increase muscle and connective tissue cross-sectional area, improve functional capacity and relieve low back pain.
Kraemer W.J. et al. Resistance training for health and performance. Curr Sports Med Rep. 2002 Jun;1(3):165-71.
Weight lifting, or resistance training, is a potent stimulus to the neuromuscular system. Depending on the specific program design, resistance training can enhance strength, power, or local muscular endurance.
Of equal importance, perhaps most notably among the elderly, are the important health benefits that may also be derived from resistance training. For example, bone density, insulin sensitivity, and co-morbidities associated with obesity can be effectively managed with resistance exercise when it is conducted on a regular basis.
Deschenes M.R. & Kraemer W.J. Performance and physiologic adaptations to resistance training. Am J Phys Med Rehabil. 2002 Nov;81(11 Suppl):S3-16.
The purpose of this study was to determine the effect resistance training has on metabolic economy during typical activities of daily living in a geriatric population.
After the resistance training program, subjects reported a significant decrease (p < or = 0.05) in perceived exertion during performance of all functional task test conditions. These results suggest that a heavy-resistance training program might affect exercise economy during daily tasks and improve ease of physical activity, thereby providing a possible mechanism for increasing quality of life in an older and geriatric population.
Hartman M.J. et al. Resistance training improve metabolic economy during functional tasks in older adults. J Strength Cond Res. 2007 Feb;21(1):91-5.
CARDIORRESPIRATORY ENDURANCE :
The 1-RM significantly increased for all exercises for both (low intensity exercise (LEX) and high intensity exercise (HEX)) groups. Aerobic capacity increased by 23,5% and 20,1% for the LEX and HEX groups respectively. Treadmill time increased by 26,4% and 23,3% for the LEX and HEX groups respectively.
Conclusion: Significant improvements in aerobic capacity and treadmill time to exhaustion can be obtained in older adults as a consequence of either high- or low-intensity resistance exercise. These findings suggest that increased strength, as a consequence of resistance exercise training, may allow older adults to reach and/or improve their aerobic capacity.
Vincent K.R. et al. Improved cardiorespiratory endurance following 6 months of resistance exercise in elderly men and women. Arch Intern Med. 2002 Mar 25;162(6):673-8.
Resistance exercise prolongs the onset of peak cardiovascular responses, decreases the cardiovascular response to exertion, and improves recovery from maximal exertion.
Vincent K.R. Strength training and hemodynamic responses to exercise. Am J Geriatr Cardiol. 2003 Mr-Apr;12(2):97-106.
Resistance training (RT) caused significant changes in the following comparisons: % fat decreased in the RT group by almost 3%, strength improved for all exercises: Le extension = +50,4%, Leg Press = +72,3% and Half squat = +83,5%; type IIB fibers decreased and IIA fibers increased; cross-sectional areas of all fiber types (I, IIA, IIB) increased significantly, and capillary to fiber ratio increased but not significantly. No differences were noted on ECG and echocardiographic data.
The RT group significantly improved treadmill performance and VO2max.
The results show that skeletal muscle in older, untrained men will respond with significant strength gains accompanied by considerable increases in fiber size and capillary density. Maximal working capacity, VO2max, and serum lipid profiles also benefit from high-intensity resistance training. Older men may not only tolerate very high intensity work loads but will exhibit intramuscular, cardiovascular, and metabolic changes similar to younger subjects.
Hagerman F.C. et al. Effects of high-intensity resistance training on untrained older men. I. Strength, cardiovascular and metabolic responses. J Gerontol A Bio Sci Med Sci. 2000 Jul;55(7):B336-46.
Ergometrical fitness was increased by approximately 15% while maximum oxygen uptake was increased by approximately 12%. Maximum strength was increased between 26% (bench press) and 38% (leg press). Furthermore, there was almost no difference in muscle strength for between the sexes for this age group (76.2 +/- 3.2 years).
Wieser M. & Haber P. The effects of systematic resistance training in the elderly. Int J Sports Med. 2007 Jan;28(1):59-65.
Results indicate that resistance training may be able to increase range of motion of a number of joints of inactive older individuals (increased sit-and-reach performance, elbow flexion, knee flexion, shoulder flexion and extension and hip flexion and extension both mid- and post-training) possibly due to an improvement in muscle strength.
Fatouros I.G. et al. The effects of strength training, cardiovascular training and their combination on flexibility of inactive older adults. Int J Sports Med. 2002 Feb;23(2):112-9.
Results indicate that resistance training by itself improves flexibility in the aged by an average of 12-28%. However, intensities greater then 60% of 1RM are more effective in producing flexibility gains, and strength improvement with resistance training is also intensity-dependent.
Fatouros I.G. et al. Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent. J Strength Cond Res. 2006 Aug;20(3):634-42.
IMPROVEMENT OF PHYSICAL CAPACITIES :
Although low intensity training improved (p<0.05) strength (42-66%), anaerobic power (10%), and mobility (5-7%), high intensity training elicited greater (p<0.05) gains (63-91% in strength, 17-25% in anaerobic power, 9-14% in mobility). CONCLUSIONS: Higher intensity training protocols induce greater gains in strength, anaerobic power, and whole body physical function of older men. Moreover, higher intensity training may maintain the gains for more prolonged periods after training ceases.
Fatouros I.G. et al. Strength training and detraining effects on muscular strength, anaerobic power, and mobility of inactive older men are intensity dependent. Br J Sports Med. 2005 Oct;39(10):776-80.
Age related declines in muscle power may be an early indicator of balance deficits and fall risk, even in nonfrail adults.
Power training improves balance, particularly using a low load, high velocity regimen, in older adults with initial lower muscle power and slower contraction.
Orr R. et al. Power training improves balance in healthy older adults. J Gerontol A Biol Sci Med Sci. 2006 Jan;61(1):78-85.
The research data indicates that significant and similar improvements in strength, endurance, and stair climbing time can be obtained in older adults as a consequence of high- or low-intensity resistance exercise training.
Vincent K.R. et al. Resistance exercise and physical performance in adults aged 60 to 83. J Am Geriatr Soc. 2002 Jun;50(6):1100-7.
Background: Muscle power (force x velocity) recedes at a faster rate than strength with age and may also be a stronger predictor of fall risk and functional decline.
Peak muscle power may be improved similarly using light, moderate, or heavy resistances, whereas there is a dose-response relationship between training intensity and muscle strength and endurance changes. Therefore, using heavy loads during explosive resistance training may be the most effective strategy to achieve simultaneous improvements in muscle strength, power, and endurance in older adults.
De Vos N.J. et al. Optimal load for increasing muscle power during explosive resistance training in older adults. J Gerontol A Biol Sci Med Sci. 2005 May;60(5):638-47.
The present strength training led to great increases in maximal strength not only in middle-aged but also in elderly men and women. The strength gains were accompanied by large increases in the maximal voluntary activation of the trained muscles.
Hakkinen K. et al. Basal concentrations and acute responses of serum hormones and strength development during heavy resistance training in middle-aged and elderly men and women. J Gerontol A Biol Sci Med Sci. 2000 Feb;55(2):B95-105.
ENDOCRINE SYSTEM :
To examine the adaptations of the endocrine system to heavy-resistance training in younger vs. older men, two groups of men (30 and 62 yr old) participated in a 10-wk periodized strength-power training program.
With training the older group demonstrated a significant increase in total testosterone in response to exercise stress along with significant decreases in resting cortisol. These data indicate that older men do respond with an enhanced hormonal profile in the early phase of a resistance training program, but the response is different from that of younger men.
Kraemer W.J. et al. Effects of heavy-resistance training on hormonal response patterns in younger vs. older men. J Appl Physiol. 1999 Sep;87(3):982-92.
Knee extensor strength and endurance, stair-climbing power, and chair-rising time improved significantly in the high intensity strength training (HI) and low intensity strength training (LI) groups compared with the Placebo-Control group (PC). Six-minute walking distance improved significantly in the HI group but not in the LI group compared with the PC group.
Conclusions: These results show strong dose-response relationships between resistance training intensity and strength gains and between strength gains and functional improvements after resistance training. Supervised HI, free weight-based training for frail elders appears to be as safe as lower intensity training but is more effective physiologically and functionally.
Seynnes O. et al. Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders. J Gerontol A Biol Sci Med Sci. 2004 May;59(5):503-9.
Progressive resistance strength training of high intensity is as safe and well tolerated as a similarly structured low-resistance exercise regimen for very frail elderly patients, but produces greater muscle strength improvements.
Sullivan D.H. et al. Effects of muscle strength training and testosterone in frail enderly males. Med Sci Sports Exerc. 2005 Oct;37(10):1664-72.
Weight Training and Chronic Heart Failure :
Background: The utility, safety and physiological adaptations of resistance exercise training in patients with chronic heart failure (CHF) are reviewed and recommendations based on current research are presented. Patients with CHF have a poor clinical status and impaired exercise capacity due to both cardiac limitations and peripheral maladaptations of the skeletal musculature. Because muscle atrophy has been demonstrated to be a hallmark of CHF, the main principle of exercise programmes in such patients is to train the peripheral muscles effectively without producing great cardiovascular stress. For this reason, new modes of training as well as new training methods have been applied. Dynamic resistance training, based on the principles of interval training, has recently been established as a safe and effective mode of exercise in patients with CHF.
Conclusions: Based on recent scientific evidence, the application of specific resistance exercise programmes is safe and induces significant histochemical, metabolic and functional adaptations in skeletal muscles, contributing to the treatment of muscle weakness and specific myopathy occurring in the majority of CHF patients. Increased exercise tolerance and peak oxygen consumption, changes in muscle composition, increases in muscle mass, alterations in skeletal muscle metabolism, improvement in muscular strength and endurance have also been reported in the literature after resistance exercise alone or in combination with aerobic exercise. According to new scientific evidence, appropriate dynamic resistance exercise should be recommended as a safe and effective alternative training mode (supplementary to conventional aerobic exercise) in order to counteract peripheral maladaptation and improve muscle strength, which is necessary for recreational and daily living activities, and thus quality of life, of patients with stable, CHF.
Volaklis K.A & Tokmakidis S.P. Resistance exercise training in patients with heart failure. Sports Med. 2005;35(12):1085-103.
In patients with chronic congestive heart failure (CHF), there is a need for complementary strength training to maintain and/or increase muscle mass and strength. The challenge is how to stress peripheral muscles intensively without creating cardiovascular overload.
With resistance training programs lasting 12 weeks, maximal strength could be improved by 15 to 50%. Improvements in maximum exercise time and peak VO2 were between 10 and 18%, in relation to baseline values. Thus, resistance exercise can be assumed as safe as aerobic exercise in clinically stable CHF.
Meyer K. Resistance exercise °n chronic heart failureólandmark studies and implications for practice. Clin Invest Med. 2006 Jun;29(3):166-9.
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