Research Review By Demetry Assimakopoulos©

Date Posted:

October 2010

Study Title:

Dose-Response Relationship of Resistance Training in Older Adults: A Meta-Analysis

Authors:

Steib S, Schoene D & Pfeifer K

Author's Affiliations:

Institute of Sports Science and Sports, University of Erlangen-Nuremberg, Erlangen, Germany.

Publication Information:

Medicine and Science in Sport and Exercise 2010; 42(5):902-14.

Background Information:

One of the most important age related degeneration processes is the loss of skeletal muscle strength and size (sarcopenia) (1,15), which is caused by numerous changes in the neuromuscular system (1,2). This loss invariably leads to decreases in physical performance and mobility, namely problems performing activities of daily living and a heightened risk of falling (9,11). Strength is very important in the preservation of independence, health status and well being of the elderly; hence, intervention strategies aim to improve or maintain strength in the elderly.

Specifically, progressive resistance training (PRT) is the most commonly used strength training intervention. There is a myriad of evidence proving its effectiveness and safety (4,8,13) in increasing functional mobility (stair climbing, chair rise, etc). However, its effectiveness in improving other aspects such as balance and other activities of daily living is unclear (2,4,8).

While the numerous studies have proven effectiveness, not many have reflected specific - and the most effective - recommendations for the type and dose of resistance training (RT) for the elderly. It was therefore, the objective of this study to determine the most appropriate frequency, duration, volume and intensity of resistance training to improve strength and physical performance in the elderly.

Pertinent Results:

Twenty-nine studies met the criteria for selection. Only 22 of these studies included adequate data. 1313 subjects were included in the 29 studies, with a mean age-range of 65-80 years. In the study which examined a frail population, the mean age was 80 years (18). Most studies, except two (12,13), included healthy, inactive and community-dwelling people.

Muscular Strength:

Training intensity: A data pool of 13 studies comparing the different intensities of PRT showed that high intensity PRT had higher effect sizes than moderate and low intensity PRT (SMD [HI vs LI] = 0.88, 95% CI = 0.21–1.55) and moderate intensity showed higher values than low intensity (SMD [HI vs MI] = 0.62, 95% CI = 0.22–1.03) for the enhancement of maximum muscular strength. The training protocols utilized in these studies were similar (3 times weekly, with 3 sets of 6-14 repetitions). However, the duration of the clinical trials varied considerably. It was concluded that high intensity training was significantly superior to low intensity training for the purposes of improving strength in this population (SMD [HI vs LI] = 1.69, 95% CI = 0.40–2.98).

Type, intensity and training volume: seven studies were included in this section. There was no significant difference between resistance training (RT) and PRT for the improvement of maximal strength (SMD [PT vs PRT] = 0.23, 95% CI = 1.42 to 0.96). Also, functional task training (FT) and PRT were compared and revealed no difference in maximal strength gains (SMD [FT vs PRT] = 0.16, 95% CI = 0.68 to 0.35). Similar findings were seen when eccentric and concentric resistance training methods were compared ((SMD [ECC vs CONC] = 0.25, 95% CI = 0.83 to 1.33).

Training frequency: Two studies examined the effect of difference training frequencies on maximal strength – one, two and three times weekly. Training twice weekly fared better than once weekly (SMD [twice vs once a week] = 1.55, 95% CI = 0.66–2.44). Training 3 times per week scored significantly better than training once per week (SMD [thrice vs once a week] = 2.57, 95% CI = 1.39–3.76). However, training 3 times weekly was not significantly different than training twice weekly (SMD [three vs two times per week] = 0.61, 95% CI = 0.23 to 1.45).

Muscle power: Power training (PT) was more effective than PRT at increasing muscle power (SMD [PT vs PRT] = 1.66, 95% CI = 0.08–3.24). One study (3) studied changes in muscle power at different training intensities in the elderly (20%, 50% and 80% of 1RM) and concluded that all intensities increased peak muscle power with no significant differences.

Muscular endurance: One study (16) reported comparable increases in muscular endurance in both their high intensity and low intensity groups (SMD [HI vs LI PRT] = 3.30. 95% CI = 9.86 to 16.46). Another study (7) concluded that PRT was superior to PT at enhancing muscular endurance ((SMD [PT vs PRT] = 2.24, 95% CI = 3.07 to 1.41). In a third study (19), it was reported that greater muscular endurance increases were seen with higher volumes (3 sets) when compared to lower volumes (1 set) (SMD [3SET vs 1SET] = 1.02, 95% CI = 0.22–1.82).

Mobility related physical function:

Training intensity: Three studies showed no difference in physical performance (stair climbing, walking speed, timed up and go) when comparing different intensities of PRT. However, circumstances were different in a study comparing high and low intensity PFT in a frail population (13): functional improvements were large in both groups. High intensity training was significantly more effective in improving the performance of the walking test (SMD = 1.72, 95% CI = 0.53–2.92) but not for stair climbing or chair rise.

Type, frequency and volume: three studies were used in this domain to compare the effectiveness PT and PRT in enhancing functional status. PT was significantly more effective in increasing the performance of chair rise (SMD [PT vs PRT] = 1.74, 95% CI = 0.39–3.10), and approached significance in improving the performance of stair climbing (SMD ‘‘stair’’ [PT vs PRT] = 1.27, 95% CI = 0.06 to 2.60). There was no significant difference in walking speed or in the timed up and go tests.

Clinical Application & Conclusions:

Training intensity: High training intensities produced the most significant gains in muscular strength (strong evidence was found for a range of intensities between 60-80% 1RM). One study (14) found that over the span of 20 weeks, the high intensity group had large strength increases in the first 12 weeks, but found no difference to the lower intensity group in the subsequent 8 weeks. This indicates a time frame of effectiveness.

This review concluded that PRT was effective in enhancing the performance of functional tasks (chair rise, stair climb, timed up and go, and walking speed). However, there were no significant differences in the extent of adaptation between high, moderate and low intensity groups. The proposed reason for this finding is that increases in strength achieved by high and moderate intensity exercise reached a threshold – after which, additional strength gains will not yield increases in performance.

Another such theory is that the higher training volumes achieved through low and moderate intensity training could be equal to the effect of high intensity training in increasing functional performance. Additionally, because of the fact that many of the subjects had little to no exercise experience, the magnitude of functional gains could have been multiplied by the fact that they had a very low baseline status.

Type of training:

Power training: Muscle power has a higher correlation to functional performance than muscular strength in older adults (6,10). In the same respect, PT is more effective than PRT in improving muscle power. However, PT and PRT are comparable in their ability to increase muscular strength.

Functional task resistance training: Functional training is effective in improving performance of activities of daily living in older adults.

Training frequency and volume: The information on this subject is particularly limited. One study (5) concluded that higher training volumes may be more effective in generating strength and endurance gains, while lower training volumes were sufficient to enhance physical performance.

No specific conclusion can be made about which resistance training method is best (functional task RT, eccentric or isometric, etc.) The evidence is too limited. However, independent of the type of resistance training, performing exercises that mimic activities of daily living is a great way to maximally increase functional performance.

At the same time, no specific conclusion can be made as to which volume or frequency is most adequate to improve muscular strength – the evidence is too limited.

In any case, it is important to work within the capabilities of the person – within their scope of intensity, volume, frequency and type. Further research is needed to determine the most adequate dose and type of resistance training for the elderly.

Study Methods:

A literature search was performed and reviewed by independent reviewers in relevant databases. Articles were included based on the consensus of the reviewers – only randomized control trials were included.

Inclusion criteria: mean age of 65 years or older; strength training was the main intervention; ithe use of relevant outcome measures, including muscular strength (1RM or MVC), muscular endurance, peak muscle power and functional tests indicating changes in mobility and; if a dose response relationship was investigated in the study with at least two different dose types.

Exclusion criteria: unsupervised exercise and; training for the purposes of treating a chronic disease.

Study Strengths / Weaknesses:

Strengths:
  1. This is the first systematic review of its kind that examines a dose response relationship for strength training in older adults. .
Weaknesses:
  1. There are a limited number of studies included in this review. The authors may have failed to gather all studies which fit into their inclusion criteria.
  2. There is the possibility of systematic error, due to the fact that internal validity of many of the trials included were not fulfilled.
  3. The authors did not take into account co-morbidities that the elderly may suffer from. In some cases, it would not be appropriate to utilize higher intensity and lower volume exercise to achieve the most optimal gains, because the risk of stroke, myocardial infarction, etc. is too high. Understand that there are times when lower intensity, high volume may be the best mode of action!

Additional References:

  1. American College of Sports Medicine. Position Stand: exercise and physical activity for older adults. Med Sci Sports Exerc. 1998;30(6):992–1008.
  2. Barry BK, Carson RG. The consequences of resistance training for movement control in older adults. J Gerontol A Biol Sci Med Sci. 2004;59(7):730–54.
  3. de Vos NJ, Singh NA, Ross DA, Stavrinos TM, Orr R, Fiatarone Singh MA. Optimal load for increasing muscle power during explosive resistance training in older adults. J Gerontol A Biol Sci Med Sci. 2005;60(5):638–47.
  4. Fiatarone MA, O’Neill EF, Ryan ND, et al. Exercise training and nutritional supplementation for physical frailty in very elderly people. N Engl J Med. 1994;330(25):1769–75.
  5. Galvao DA, Taaffe DR. Resistance exercise dosage in older adults: single- versus multiset effects on physical performance and body composition. J Am Geriatr Soc. 2005;53(12): 2090–7.
  6. Hazell T, Kenno K, Jakobi J. Functional benefit of power training for older adults. J Aging Phys Act. 2007;15(3):349–59.
  7. Henwood TR, Riek S, Taaffe DR. Strength versus muscle powerspecific resistance training in community-dwelling older adults. J Gerontol A Biol Sci Med Sci. 2008;63(1):83–91.
  8. Latham N, Anderson C, Bennett D, Stretton C. Progressive resistance strength training for physical disability in older people. Cochrane Database Syst Rev. 2003;(2).
  9. Lauretani F, Russo CR, Bandinelli S, et al. Age-associated changes in skeletal muscles and their effect on mobility: an operational diagnosis of sarcopenia. J Appl Physiol. 2003;95(5):1851–60.
  10. Porter MM. Power training for older adults. Appl Physiol Nutr Metab. 2006;31(2):87–94.
  11. Rantanen T, Guralnik JM, Ferrucci L, Leveille S, Fried LP. Coimpairments: strength and balance as predictors of severe walking disability. J Gerontol A Biol Sci Med Sci. 1999;54(4):M172–6.
  12. Sayers SP, Bean J, Cuoco A, LeBrasseur NK, Jette A, Fielding RA. Changes in function and disability after resistance training: does velocity matter?: a pilot study. Am J Phys Med Rehabil. 2003;82(8):605–13.
  13. Seynnes O, Fiatarone Singh MA, Hue O, Pras P, Legros P, Bernard PL. Physiological and functional responses to lowmoderate versus high-intensity progressive resistance training in frail elders. J Gerontol A Biol Sci Med Sci. 2004;59(5):503–9.
  14. Taaffe DR, Pruitt L, Pyka G, Guido D, Marcus R. Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women. Clin Physiol. 1996;16(4):381–92.
  15. Vandervoort AA. Aging of the human neuromuscular system. Muscle Nerve. 2002;25(1):17–25.
  16. Vincent KR, Braith RW, Feldman RA, et al. Resistance exercise and physical performance in adults aged 60 to 83. J Am Geriatr Soc. 2002;50(6):1100–7.