Effects of fitness and vibration training on muscle quality: a 1-year postintervention follow-up in older men.

OBJECTIVE: To evaluate the residual effects of fitness and whole-body vibration (WBV) training in older men 1 year after completion of the interventions. DESIGN: A 1-year follow-up of a randomized controlled trial comparing the effects of 1 year of fitness training, including combined resistance and aerobic (R+A) training and WBV training, with a control (CON) group. SETTING: University training center. PARTICIPANTS: Adult men (N=72) between 60 and 80 years of age. Response rate was 80%, 92%, and 90% in the R+A training (n=20), WBV training (n=23), and CON (n=29) groups, respectively. INTERVENTIONS: The intervention groups exercised 3 times weekly during 1 year. The R+A training group performed a standard training program, combining resistance exercises and aerobic training, following the American College of Sports Medicine guidelines. The WBV training group performed unloaded static and dynamic leg exercises on a vibration platform. The CON group did not participate in any training program. MAIN OUTCOME MEASURES: Muscle volume, isometric and concentric muscle strength, muscle quality, and muscle power. RESULTS: Both interventions had resulted in comparable increases in muscle quality characteristics. No significant changes had been found in the CON group. During the 1-year follow-up period, the R+A (-4.05%, P=.006) and WBV (-2.45%, P<.0001) training groups had lost most of their gains in muscle volume. However, isometric muscle strength was preserved in the R+A training group (+1.65%, P=.745), resulting in an increase in muscle quality (+7.97%, P=.034). In the WBV training group, muscle power decreased (-6.10%, P<.0001) but remained significantly higher than at baseline (P=.038). Except for a strong decrease in muscle power, no significant changes were found in the CON group. CONCLUSIONS: One year of R+A and/or WBV training can equally reverse the adverse effects of aging on muscle quality in older men, but their residual impact after follow-up is different.

Long-term impact of strength training on muscle strength characteristics in older adults.

OBJECTIVE: To evaluate the long-term preventive impact of strength training on muscle performance in older adults. DESIGN: A 7-year follow-up on a 1-year randomized controlled trial comparing the effects of combined resistance training and aerobic training and whole-body vibration training on muscle performance. SETTING: University training center. PARTICIPANTS: Men and women (N=83; control [CON] group, n=27; strength-training intervention [INT] group, n=56) between 60 and 80 years of age. INTERVENTIONS: The INT group exercised 3 times weekly during 1 year, performing a combined resistance training and aerobic training program or a whole-body vibration training program. The former training program was designed according to American College of Sports Medicine guidelines. The whole-body vibration training program included unloaded static and dynamic leg exercises on a vibration platform. The CON group did not participate in any training program. MAIN OUTCOME MEASURES: Static strength (STAT), dynamic strength at 60°/s (DYN60) and at 240°/s (DYN240), speed of movement at 20% (S20). RESULTS: From baseline to postintervention, muscle performance did not change in the CON group, except for S20 (+6.55%±2.88%, P<.001). One year of strength training increased (P≤.001) STAT (+11.46%±1.86%), DYN60 (+6.96%±1.65%), DYN240 (+9.25%±1.68%), and S20 (+7.73%±2.19%) in the INT group. Between baseline and follow-up, muscle performance decreased (P<.001) in both groups. However, STAT and DYN60 showed a significantly lower loss in the INT group (-8.65%±2.35% and -7.10%±2.38%, respectively) compared with the CON group (-16.47%±2.69% and -15.08%±2.27%, respectively). This positive impact might be due to the preservation of the training-induced gains, given the similar annual decline rates in both groups from postintervention to follow-up. Additionally, in trained participants, aging seems to impact velocity-dependent strength and power more compared with basic strength, as the total losses in DYN240 (CON, -15.93%±2.64%; INT, -11.39%±1.95%) and S20 (CON, -14.39%±2.10%; INT, -13.16%±1.72%) did not differ significantly between the groups. CONCLUSIONS: A 1-year strength-training intervention results in an improved muscle performance in older adults 7 years after their enrollment in the intervention. However, an extensive exercise program cannot attenuate the age-related decline once the intervention stops.

"Every step counts!": effects of a structured walking intervention in a community-based senior organization.

This study evaluated "Every Step Counts!"- a 10-wk, structured walking intervention in a community-based senior organization - on promoting physical activity participation, fitness, and well-being among older adults (age ≥ 55 yr). The intervention prescribed pedometer-defined walks in weekly walking schedules. These were fitness-tailored and structured in walking load (intensity/volume) according to the principles of training progression. This intervention was offered as a social activity at meeting points of a community-based senior organization. Twenty-nine meeting points (n = 432) constituted the intervention condition. Ten meeting points (n = 148) formed the wait-list control condition. Measurements were organized at intervention start (pretest) and end (posttest). Intention-to-treat linear mixed models showed small positive intervention effects on physical activity, fitness, and aspects of well-being. These results confirm the effectiveness of structured walking interventions with systematic training progression and underscore the value of community-based senior organizations as intervention settings for older adults.

Impact of external resistance and maximal effort on force-velocity characteristics of the knee extensors during strengthening exercise: a randomized controlled experiment.

It remains controversial whether maximal effort attained by high external resistance is required to optimize muscle adaptation to strengthening exercise. Here, we compared different training protocols reaching maximal effort with either high-resistance (HImax, 80% of 1-repetition maximum [1RM]) or low-resistance (LOmax, ≤40% 1RM). Thirty-six young volunteers were randomly assigned to 9 weeks of leg extension training at either HImax (1 set of 10-12 repetitions at 80% 1RM), LO (1 set of 10-12 repetitions at 40% 1RM, no maximal effort), or LOmax (1 set of 10-12 repetitions at 40% 1RM, preceded [no rest] by 60 repetitions at 20-25% 1RM). Knee extension 1RM was measured preintervention and postintervention and before the 7th, 13th, and 19th training sessions. Preintervention and postintervention, knee extensor static (PTstat) and dynamic (PTdyn) peak torque, maximal work (MW), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat were recorded with a Biodex dynamometer. All the groups showed a significant increase in 1RM, with a greater improvement in HImax from the 13th session on (p < 0.05). The HImax was the only group that significantly increased PTstat (+7.4 ± 8.1%, p = 0.01). The LOmax showed a significantly greater increase in S20 (+6.0 ± 3.2%), PTdyn (+9.8 ± 5.6%), and MW (+15.1 ± 10.6%) than both HImax and LO (p = 0.044 for S20, p = 0.030 for PTdyn, p = 0.025 for MW) and was the only group that increased in S40 (+7.7 ± 9.7%, p = 0.032). In conclusion, significant differences between HImax and LOmax on force-velocity characteristics of the knee extensors were found, although maximal effort was achieved in both training regimens. Thus, LOmax may not be considered as a replacement for HImax but rather as an alternative with different training-specific adaptations.

Force-velocity characteristics of the knee extensors: an indication of the risk for physical frailty in elderly women.

OBJECTIVES: To examine the relationship between muscle strength, speed of movement, muscle mass (MM), and functional performance in elderly women and to determine optimal threshold values below which physical frailty occurs. DESIGN: Survey. SETTING: University-based laboratory. PARTICIPANTS: Institutionalized women (N=123; mean age, 79.67 ± 5.2y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Force-velocity characteristics of the knee extensors were evaluated by using isometric, isokinetic, and ballistic tests on a motor-driven dynamometer. Isometric (ISOM) strength, dynamic strength, maximal speed of movement (SoM, unloaded), and speed of movement with standardized resistance of 20% (S(20)), 40% (S(40)), and 60% (S(60)) of the isometric maximum were recorded. MM of the upper leg was determined by using computed tomography. The modified Physical Performance Test (mPPT) was used to assess functional performance. RESULTS: Force-velocity characteristics (r varied from .31-.68) and MM (r=.41) correlated significantly with functional performance (P<.05). In a forward stepwise regression model, only SoM and ISOM strength remained independently associated with mPPT score (R(2)=.49), with SoM accounting for most of the variance. The threshold value that optimally differentiates between women with mild (mPPT score, 25-31) or without (mPPT score ≥32) physical frailty was 350°/s for SoM and 1.46N m/kg for ISOM strength. Sensitivity and specificity ranged from 74% to 77% and 71% to 77%, respectively. CONCLUSIONS: SoM is a key component in the onset of functional difficulties in elderly women. Exercise interventions specifically targeting muscle power (by including exercises at high velocities) thus might be crucial to prevent functional decline.

Longitudinal impact of aging on muscle quality in middle-aged men.

The present follow-up study aims at assessing the longitudinal changes in muscle quality after an interval of 9.45 years in middle-aged men. In addition, the relative contribution of muscle mass, muscle strength, and muscle power at middle age to these changes was investigated. The results showed a small, though unexpected, increase in total body and leg muscle mass (respectively 0.22 ± 0.04 and 0.29 ± 0.06 % yearly, p < 0.0001), whereas basic strength (-0.71 to -0.87 % yearly, p < 0.0001) and velocity-dependent strength and power (-1.19 to -1.86 % yearly, p < 0.0001) declined. Consequently, muscle quality, defined as the ratio of basic strength or velocity-dependent strength and power to muscle mass decreased (-1.46 to -2.43 % yearly, p < 0.0001) from baseline to follow-up. We found that baseline basic strength is a strong determinant of the decline in muscle quality basic strength with advancing age, whereas only a small part of the age-associated decline in muscle quality based on velocity-dependent strength and power could be explained. To conclude, our results indicate that muscle becomes less efficient at middle age and that baseline muscle strength is a strong predictor of this change. These findings imply that unmeasured neural factors, influencing both contraction speed and the capacity of muscle to produce strength, are possibly other involved determinants. Therefore, timely interventions including strength training and higher-velocity strength training at middle age are recommended.

Effectiveness of a lifestyle physical activity versus a structured exercise intervention in older adults.

Two groups of sedentary older adults, participating in either a lifestyle physical activity intervention (LIFE, n = 60) or a structured exercise intervention (STRU, n = 60), were compared with a control group (CO, n = 66) in terms of physical fitness and cardiovascular risk factors. Participants in LIFE were stimulated to integrate physical activity into their daily routines and received an individualized home-based program. Participants in STRU completed 5 supervised training sessions every 2 wk in a fitness center. Both interventions lasted 11 months and focused on endurance, strength, flexibility, and postural/balance exercises. The results revealed that the interventions were equally effective in improving functional performance. STRU was more effective than LIFE in improving cardiorespiratory and muscular fitness. Limited effects emerged on cardiovascular risk, with STRU improving in total cholesterol and HDL. Consequently, interventions aiming at reducing cardiovascular risks among sedentary elderly should focus on long-term changes in physical activity behavior.