Upper Body Mean Strength
As expected, POST values were significantly higher than PRE (P = .01). Figure 1 represents the time course of the changes in upper body mean strength for training duration and post exercise status. 6MP values were also significantly higher than PRE (P = .01); however, POST values were significantly higher than 6MP (P = .01). There were significant 2-way interactions for time X training duration (P = .01) and time X exercise status (P = .01). There was not a significant 3-way interaction (time X training duration X exercise status) or an interaction between training duration and postexercise status on the basis of the percent changes for the groups. The group that trained for 40 weeks had significantly higher POST (mean 42.1 ± SE 2.1 kg) and 6MP (36.9 ± SE 1.8 kg) upper body mean strength compared to PRE values (28.5 ± SE 1.7 kg, P = .01); however, the upper body mean strength at 6MP was significantly lower than the POST value (P = .01). Participants that trained for 80 weeks exhibited significantly higher POST (36.1 ± SE 2.6 kg, P = .01) and 6MP (37.0 ± SE 2.7 kg, P = .01) values than PRE (29.7 ± SE 2.1 kg), but there was no statistical difference between 6MP and POST (P = .37). The group that completed the 40-week intervention had a significantly greater percent increase in upper body strength from PRE to POST (52.2 ± SE 4.4%, P = .01) compared to the 80-week intervention group (22.1 ± SE 2.5%). However, the 40-week group then lost strength (-11.0 ± SE 2.3%) while the 80- week group continued to gain (3.6 ± SE 2.5%, P = .01).
For the Ex group, POST (40.6 ± SE 2.4 kg) and 6MP (40.0 ± SE 2.3 kg) values were significantly higher than PRE values (29.6 ± SE 1.8 kg, P = .01) but there was no difference between POST and 6MP upper body mean strength values. For the NoEx group, POST (38.1 ± SE 2.3 kg) and 6MP (33.2 ± SE 1.8 kg) values were also significantly higher than PRE values (28.4 ± SE 2.0 kg, P = .01); however, 6MP values were significantly lower than POST upper body strength values (P = .01). There were similar percent changes in upper body mean strength from PRE to POST for both the Ex and NoEx groups, regardless of training duration. The percent changes from PRE to 6MP, for those that continued to exercise, had a significantly greater changes (38.0 ± SE 4.0%, P = .01) compared to the NoEx group (22.9 ± SE 4.4%). Finally, in examining the percent changes from POST to 6MP, there was a significantly greater increase for the Ex group (0.4 ± SE 2.6%, P = .02) compared to the NoEx group (-10.9 ± SE 2.4%).
Lower Body Mean Strength
The time courses for each training duration and post exercise group can be seen in Figure 2. There was only a significant main effect for time (P = .01) from the 3-way repeated-measures ANOVA (time X training duration X exercise status) with both POST (P = .01) and 6MP values (P = .01) being significantly higher than PRE. Unlike upper body mean strength, there was no significant difference between 6MP and POST values. There were significant 2-way interactions for time X training duration (P = .01) and time X exercise status (P = .01).
Participants who trained for 40 weeks had significantly higher POST (77.8 ± SE 4.1 kg, P = .01) and 6MP (71.5 ± SE 3.4 kg, P = .01) values compared to PRE (46.8 ± SE 2.6 kg); however, the mean lower body strength at 6MP was significantly lower than POST (P = .04). The participants who completed the 80-week training program had POST (68.0 ± SE 4.1 kg, P = .001) and 6MP (75.3 ± SE 5.0 kg, P = .01) strength values that were significantly higher than PRE (52.1 ± SE 3.1 kg); in addition, the 6MP values were significantly higher than POST values (P = .01). The 40-week cohort had a percentage increase in their lower body mean strength of (71.1 ± SE 5.9%) from PRE to POST, which was significantly more than the 80-week group (33.3 ± SE 5.0%, P = .01). During the unsupervised period (POST to 6MP), the 40-week group lost significantly more strength than the 80-week group (-5.3 ± SE 3.2% vs 10.5 ± SE 2.8%, P = .01). These differences in gains and losses over the entire duration of the study (PRE to 6MP) resulted in a nonsignificant difference between the percentage gains on the basis of training duration: 40 week, 60.5 ± SE 6.3% versus 80 week, 47.1 ± SE 6.3%.
For the Ex group, POST (76.4 ± SE 4.1 kg) and 6MP (80.5 ± SE 4.2 kg) values were significantly higher than PRE values (50.4 ± SE 2.6 kg, P = .01), but there was no difference between POST and 6MP lower body mean strength values. Similar results were observed for the NoEx group, with POST (70.1 ± SE 4.1 kg) and 6MP (64.2 ± SE 3.2 kg) values being significantly higher than PRE values (47.6 ± SE 3.2 kg, P = .01) and there was only a trend for a difference between 6MP values and POST lower body strength values (P = .07). Figure 3 graphically represents the percent changes in upper and lower body mean strength from POST to 6MP for each training duration and exercise grouping. The percent change for the training period was similar for the Ex and NoEx groups (56.5 ± SE 7.0% and 52.3 ± SE 5.6%, respectively). During the unsupervised period, the Ex group continued to gain strength (7.5 ± SE 3.4%), while the NoEx group regressed (−5.6 ± SE 2.7%); this difference was significant (P = .01) and led to total change in strength (PRE to 6MP) also being significantly different on the basis of exercise status: Ex, 64.1 ± SE 6.2% versus NoEx, 43.1 ± SE 6.2%, P = .01.
A unique aspect of our research design is that the individuals who decided not to continue to exercise at the end of the formal training periods provided a pool of participants that allowed us to examine aspects of detraining, whereas the participants who continued to exercise on their own in the community at the end of the formal training programs allowed us to examine the effects of a nonsupervised resistance training on the ability to maintain or improve on the benefits achieved from the supervised programs. While this research approach allows for the gathering of some novel information, it also presents some potential problems that make the interpretation of the findings somewhat difficult and less robust to standard statistical analyses.
Our findings supported the hypothesis that strength values 6 months after supervised training were higher than the pretraining strength measures for all participants, regardless of training duration or posttraining exercise status. Therefore, older participants were able to retain some of their resistance training benefits, whether they continued toexercise on their own or not. This indicates that while regression of strength does occur, it may occur at a pace close to that seen in young adults12 and not be altered because of age-related changes in protein intakes, protein synthesis rates, and age-related muscle loss.
The results from our study confirm that older men and women can significantly improve both upper and lower body strength following a supervised, progressive overload resistance training program and that these participants could easily tolerate a 40- or 80-week training program, because no adverse events or injuries were reported throughout the training programs. It is also important to note that improvements in strength continued over the entire 40- or 80-week periods with the progressive overload model, similar to the finding of McCartney et al.6 Generally, the improvements for the lower body were significantly greater for both men and women than for the upper body (58.2% and 52.6% vs 38% and 39.8%, respectively), regardless of the total training time. Compliance was also similar to McCartney et al,6 who reported a dropout rate of 12% with about 84% of the training sessions attended over two 10-month periods. Somewhat surprising, in each analyses, there was no main effect for exercise status (Ex or NoEx), suggesting that changes observed in strength following the training program were independent of whether or not participants continued to exercise. This result may arise from a loss of statistical power because of multiple comparisons being performed on a limited number of available participants in each subgroup.
We found that the 6MP strength measures were generally lower than the POST values. The one exception occurred for the group of participants that completed the 80-week training program and then continued to exercise on their own: upper body strength values increased through their own exercise programs compared to POST values (8.7%), and lower body strength increased 17.7%. The percent declines in upper and lower body strength over the 6-month period following the training were greatest for those who completed the 40-week supervised program and then decided to stop exercising (— 15.2% and —9.1%, respectively); followed by those that competed the 40-week program and continued to exercise on their own (— 7.0% and —1.7%, respectively); and finally those that completed the 80-week program and decided to stop training (—4.1% and —0.2%, respectively). The self-selecting nature of the participants that chose to extend their supervised training period to 80 weeks may have been the driving force for their continued gains through the unsupervised period.
Generally, the magnitude of strength declines we found 6MP training is in agreement with other more traditional detraining studies. McCartney et al6 reported that overall strength declined by 9% after a 2-month layoff. Porter et al11 reported smaller declines in strength after 1 year of training and a 1 year unsupervised period of 8% for the knee extensors and lat pull-down. Henwood and Taaffe13 reported declines of 16% and 17% for total body strength over a 6-month detraining period for previous high-velocity and strength trained groups, respectively. The results of this study were considerably less than the losses observed by Henwood and Taaffe.13 While the current study generally found that strength did significantly decline over the 6-month lapse, the 6MP levels were still greater than PRE levels; this is contrary to the findings of Kalapotharakos et al,14,15 who reported that strength returned to baseline levels after 6 weeks of detraining. In older adults (61–75 years, men), 10 weeks of moderate training resulted in modest strength gains in knee flexion and extension, which was lost over 6 weeks of detraining.13 The group also tested very old men (80 years and older) and found some mild retention of strength after 8 weeks of training and 6 weeks of detraining: 13% greater than PRE for lower extremity and 11% for the upper extremity.15 The findings of this study are similar to Taaffe and Marcus,16 who reported muscular strength declined during the detraining period by 7% overall. A difference between Taaffe and Marcus's protocol and the present study was the instruction to not exercise duringthe detraining period by the previous study,16 while the present study encouraged participants to exercise independently. No specific training program (frequency, loads, or progression) was suggested.
The amount of decline appeared to be greater for those completing the 40-week program than for those completing the 80-week program. In contrast to the 5-year (2 years of training, 3 years of detraining: 150% of training time) study of Smith et al,8 our study showed greater retention of both upper and lower body strength over the detraining period. The extrapolated timeline for the current study and the data of Smith et al8 mirrors that of Harris et al,17 who found that some strength was lost at 6 weeks of detraining after 18 weeks of training (33% training time), but a greater loss occurred from week 6 to week 20 (111% of training time) of detraining. After the 20-week detraining period, older adults retained greater strength than they began the 18- week training regimen with: total body 14% to 20%, upper body 6% to 17%, and lower body 15% to 27%.17 Similar to Taaffe and Marcus,16 participants were discouraged from exercising during the detraining period. Our findings do not support a relative time-related reduction in strength retention, as there was not a training duration effect on the percent of strength lost during the detraining period for either the lower or the upper extremities. This may be a result of the sample size of this study. On the basis of previous research, one would expect to see statistically significant declines in strength following 40 weeks of training and 24 weeks of detraining (60% of training time) compared to the 80-week group (30% of training time).
The focus on hip musculature during the supervised training period, 5 of the 7 lower extremity lifts directly involved the hips, should have decreased the risk of falling for the participants. Hip abduction strength and power, in particular, has been linked to fall risk in several studies.18,19 This focuses on decreasing falls from perturbations lateral to the direction of motion. Knee extension strength has also been shown to be important in arresting falls as the quadriceps are the main muscle groups that extend the knee.18 Participants in the current study performed 2 exercises with the quadriceps: seated knee extension and leg press on a sled. While the number of falls was not recorded for this study, no falls were reported by the participants either. The improved maintenance of the lower extremity mean strength, compared to the upper extremity strength, may be indicative of a lowered risk of falls for these participants.
A limitation of the current study was the design, because the results of the relative duration of the decline were most likely confounded by the continuation of an exercise regimen by some, but not all participants, in both the 40- and 80-week training groups following the cessation of the supervised training program. Again, the self-selecting nature of those that continued to exercise after the supervised training period likely confounded the overall results of this study. A lack of quantification of the amount of resistance training (both intensity and volume) further confounds the results of this study.
Older adults were able to easily tolerate and demonstrate significant increases in muscular strength following either 40-week or 80-week supervised strength training programs. Both groups were able to maintain upper body and lower body strength at levels that were significantly greater than pretraining levels, regardless whether they continued to exercise or not. However, the longer-duration training program provided a greater, although non-statistically significant, ability to maintain strength at higher levels at 6MP training compared to the strength values obtained at the end of the two different training periods. Strength was better maintained for the lower body compared to the upper body for both groups.
Perhaps an important aspect of these findings is that strength values declined for both groups, regardless of training status. Because these individual may actually represent a more physically active group of individuals compared to the reference population (because they actually volunteered to train for either 40 or 80 weeks), much greater declines in strength for a more sedentary population should be expected.
It should also be mentioned that the results should be viewed with some caution because the research design allowed for obtaining novel information regarding exercise adherence after a supervised program and about detraining, but it also resulted in some difficulties in statistical interpretation.
1. Esposito F, Malgrati D, Veicsteinas D, Orizio C. Time and frequency domain analysis of electromyogram and sound myogram in the elderly. Eur J Appl Physiol. 1996;73:503–510.
2. Hughes V, Frontera W, Wood M, et al. Longitudinal muscle strength changes in older adults: influence of muscle mass, physical activity, and health. J Gerontol A Biol Sci Med Sci. 2001;56(5):B209-B217.
3. Booth F, Weeden S, Tsengm B. Effect of aging on human skeletal muscle and motor function. Med Sci Sports Exerc. 1994;26:556–560.
4. Charette S, McEvoy L, Pyka G, et al. Muscle hypertrophy response to resistance training in older women. J Appl Physiol. 1991;70:1912–1916.
5. Laforest S, St-Pierre M, Cyr J, Gayton G. Effects of age and regular exercise on muscle strength and endurance. Eur J Appl Physiol. 1990;60:104–111.
6. McCartney N, Hicks A, Martin J, Webber C. A longitudinal trial of weight training in the elderly: continued improvements in year 2. J Gerontol A Biol Sci Med Sci. 1996;51(6):B425-B433.
7. Pyka G, Linderberger E, Charette S, Marcus R. Muscle strength and fiber adaptations to a year-long resistance training program in elderly men and women. J Gerontol. 1994;49:M22-M27.
8. Smith K, Winegard K, Hicks AL, McCartney N. Two years of resistance training in older men and women: the effects of three years of detraining
on the retention of dynamic strength. Can J Appl Physiol. 2003;28:462–474.
9. Connelly D, Vandervoort A. Effects of detraining
on knee extensor strength and functional mobility in a group of elderly women. J Orthoped Sports Phys Ther. 1997;26:340–346.
10. Taaffe DR, Henwood TR, Spry N, Joseph D, Turner D, Newton RU. Alteration in muscle attenuation following detraining
and retraining in resistance-trained older adults. Gerontology. 2009;55:217–223.
11. Porter M, Nelson M, Fiatarone-Singh M, et al. Effects of a long term resistance training and detraining
on strength and physical activity in older women. J Aging Phys Act. 2002;10:260–270.
12. Lemmer JT, Hurlbut DE, Martel GF, et al. Age and gender responses to strength training
. Med Sci Sports Exerc. 2000;32:1505–1512.
13. Henwood TR, Taaffe DR. Detraining
and retraining in older adults following long-term muscle power or muscle strength specific training. J Gerontol A Biol Sci Med Sci. 2008;63(7):751–758.
14. Kalapotharakos VI, Smilios I, Parlavatzas A, Tokmakidis SP. The effect of moderate resistance strength training
on muscle strength and power in older men. J Geriatr Phys Ther. 2007;30:109–113.
15. Kalapotharakos VI, Diamantopoulos K, Tokmakidis SP. Effects of resistance training and detraining
on muscle strength and functional performance of older adults aged 80 to 88 years. Aging Clin Exp Res. 2010;22:134–140.
16. Taaffe D, Marcus R. Dynamic muscle strength alterations to detraining
and retraining in elderly men. Clin Physiol. 1997;17:311–324.
17. Harris C, DeBeliso M, Adams KJ, Irmischer BS, Gibson TA. Detraining
in the older adult: effects of prior training intensity on strength retention. J Stren Cond Res. 2007;21:813–818.
18. Lloyd BD, Williamson DA, Sigh NA, et al. Recurrent and injurious falls in the year following hip fracture: a prospective study of the incidence and risk factors from the Sarcopenia and Hip Fracture study. J Gerontol A Biol Sci Med Sci. 2009;64(5):599–609.
19. Hilliard MJ, Martinez KM, Janssen I, et al. Lateral balance factors predict future falls in community-living older adults. Arch Phys Med Rehabil. 2008;89:1708–1713.
Keywords:Copyright © 2012 the Section on Geriatrics of the American Physical Therapy Association
detraining; older persons; strength training