Effects of eccentric training on torque-angular velocity-power characteristics of elbow flexor muscles in older women

Age-related blunting of serial sarcomerogenesis and mechanical adaptations following 4 wk of maximal eccentric resistance training

During aging, muscles undergo atrophy, which is partly accounted for by a loss of sarcomeres in series. Serial sarcomere number (SSN) is associated with aspects of muscle mechanical function including the force-length and force-velocity-power relationships; hence, the age-related loss of SSN contributes to declining performance. Training emphasizing eccentric contractions increases SSN in young healthy rodents; however, the ability for eccentric training to increase SSN in old age is unknown. Ten young (8 mo) and 11 old (32 mo) male Fisher344/BN rats completed 4 wk of unilateral eccentric plantar flexion training. Pre- and posttraining, the plantar flexors were assessed for the torque-frequency, passive torque-angle, and torque-velocity-power relationships. The soleus, lateral gastrocnemius (LG), and medial gastrocnemius (MG) were harvested for SSN assessment via laser diffraction, with the untrained leg used as a control. In the untrained leg/pretraining, old rats had lower SSN in the soleus, LG, and MG, lower maximum torque, power, and shortening velocity, and greater passive torque than young. Young showed increased soleus and MG SSN following training. In contrast, old had no change in soleus SSN and experienced SSN loss in the LG. Pre- to posttraining, young experienced an increase in maximum isometric torque, whereas old had reductions in maximum torque, shortening velocity, and power, and increased passive torque. Our results show that although young muscle has the ability to add sarcomeres in response to maximal eccentric training, this stimulus could be not only ineffective, but also detrimental to aged muscle leading to dysfunctional remodeling.NEW & NOTEWORTHY The loss of sarcomeres in series with age contributes to declining muscle performance. The present study investigated whether eccentric training could improve performance via serial sarcomere addition in old muscle, like in young muscle. Four weeks of maximal eccentric training induced serial sarcomere addition in the young rat plantar flexors and improved in vivo performance, however, led to dysfunctional remodeling accompanied by further impaired performance in old rats.

Inertial Training Improves Strength, Balance, and Gait Speed in Elderly Nursing Home Residents

Purpose

The aim of the study was to evaluate the impact of inertial training on upper and lower extremity strength in the elderly. The study also assessed the influence of inertial training on their independence, balance, and speed and quality of gait.

Methods

Twenty physically inactive older residents of a nursing home (6 women and 14 men; age, 76.7 ± 8.77 years) were randomized to a training (T; n = 10) or control group (C; n = 10). The T group performed inertial training twice a week for 6 weeks using a Cyklotren inertial device. Each training session included 12 exercise sets involving the elbow and knee flexor and extensor muscles (3 sets per single muscle group). The training loads were 10 and 20 kg for the upper and lower extremities, respectively. Before and after training, the maximum force of trained muscles was evaluated under training conditions. Functional tests were also completed.

Results

Participants from the T group had significantly increased (37.1–69.1%) elbow and knee flexor and extensor muscle strength. Improvement in upper and lower limb strength in non-specific conditions was also noted; 23.3% and 40.6%, respectively. Functional abilities improved significantly in the T group (Tinetti balance test: 29%, Tinetti gait tests: 18.6%, and gait speed (8-Foot Up-and-Go): 12.8%), while remaining unchanged in C.

Conclusion

We strongly recommend a daily routine of inertial training for older adults. Benefits from inertial training can reduce the risk of falls and increase the safety and independence of the elderly.

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Effects of Eccentric-Focused Versus Conventional Training on Lower Limb Muscular Strength in Older People: A Systematic Review With Meta-Analysis

Eccentric-focused training promotes greater gains in muscle strength compared to other types of training in adults. However, for older people, these findings are still not well understood. A systematic review and meta-analysis were performed using manuscripts that performed eccentric-focused (ET) and conventional resistance training (CT) at least four weeks and evaluated maximum muscle strength through tests of maximum repetitions in weight machine exercises (knee extension and leg press exercises). Five studies were included (n=138). Increases in muscle strength were found in both resistance training groups, without difference between them through meta-analysis. However, a large effect size has been observed only in ET. The findings suggest that resistance training protocols are similar to improve maximal strength in older people, despite larger effect sizes for eccentric-focused training.

Comparing the effects of two distinct eccentric modalities to traditional resistance training in resistance trained, higher functioning older adults

BACKGROUND

The effects of eccentric resistance exercise are of interest in the older adult cohort, but to our knowledge, there is no research on the relative effects of different eccentric modalities on a range of outcomes in higher functioning, resistance trained older adults.

METHODS

33 resistance-trained older adults (aged 67±4.5years) were randomized into one of three supervised training groups: traditional (TRE), eccentric only (ERE) or eccentrically biased resistance exercise (EBRE) on a 45°, plate-loaded leg press machine. Participants trained twice per week with maximal strength, functional capacity, body composition and blood biomarkers measured before and after the eight-week intervention.

RESULTS

Both eccentric and concentric strength, and important functional tasks for independent living significantly improved independent of group. Body composition and blood biomarkers were found to significantly improve in the EBRE group only however, no statistical differences were found between groups.

CONCLUSION

Compared to traditional resistance training, the two eccentric modalities investigated here were equally effective for improvements in maximum muscular strength, functional capacity, body composition and metabolic biomarkers. When training the resistance trained older adult, very heavy isoinertial external loads (at least 70% of one repetition maximum) are effective irrespective of contraction mode. With heavy strength training, resistance trained older adults can continue to expect improvements in health and function.

The effect of virtual reality-based eccentric training on lower extremity muscle activation and balance in stroke patients

[Purpose] The purpose of this study was to examine the effect of virtual reality-based eccentric training on lower extremity muscle activity and balance in stroke patients. [Subjects and Methods] Thirty stroke patients participated, with 15 patients allotted to each of two eccentric training groups: one using a slow velocity (group I) and one using a fast velocity (group II). The virtual reality-based eccentric training was performed by the patients for 30 minutes once a day, 5 days a week, for 8 weeks using an Eccentron system. Surface electromyography was used to measure the lower extremity muscle activity, while a BioRescue was used to measure balancing ability. [Results] A significant difference in lower extremity muscle activation and balance ability was observed in group I compared with group II. [Conclusion] This study showed that virtual reality-based eccentric training using a slow velocity is effective for improving lower extremity muscle activity and balance in stroke patients.

Chronic Eccentric Exercise and the Older Adult

Eccentric exercise has gained increasing attention as a suitable and promising intervention to delay or mitigate the known physical and physiological declines associated with aging. Determining the relative efficacy of eccentric exercise when compared with the more conventionally prescribed traditional resistance exercise will support evidence-based prescribing for the aging population. Thus, original research studies incorporating chronic eccentric exercise interventions in the older adult population were included in this review. The effects of a range of eccentric exercise modalities on muscular strength, functional capacity, body composition, muscle architecture, markers of muscle damage, the immune system, cardiovascular system, endocrine system, and rating of perceived exertion were all reviewed as outcomes of particular interest in the older adult. Muscular strength was found to increase most consistently compared with results from traditional resistance exercise. Functional capacity and body composition showed significant improvements with eccentric endurance protocols, especially in older, frail or sedentary cohorts. Muscle damage was avoided with the gradual progression of novel eccentric exercise, while muscle damage from intense acute bouts was significantly attenuated with repeated sessions. Eccentric exercise causes little cardiovascular stress; thus, it may not generate the overload required to elicit cardiovascular adaptations. An anabolic state may be achievable following eccentric exercise, while improvements to insulin sensitivity have not been found. Finally, rating of perceived exertion during eccentric exercise was often significantly lower than during traditional resistance exercise. Overall, evidence supports the prescription of eccentric exercise for the majority of outcomes of interest in the diverse cohorts of the older adult population.

Effects of eccentric-focused and conventional resistance training on strength and functional capacity of older adults

The aim of the study was to assess the effect of eccentric training using a constant load with longer exposure time at the eccentric phase on knee extensor muscle strength and functional capacity of elderly subjects in comparison with a conventional resistance training program. Twenty-six healthy elderly women (age = 67 ± 6 years) were randomly assigned to an eccentric-focused training group (ETG; n = 13) or a conventional training group (CTG; n = 13). Subjects underwent 12 weeks of resistance training twice a week. For the ETG, concentric and eccentric phases were performed using 1.5 and 4.5 s, respectively, while for CTG, each phase lasted 1.5 s. Maximum dynamic strength was assessed by the one-repetition maximum (1RM) test in the leg press and knee extension exercises, and for functional capacity, subjects performed specific tests (6-m walk test, timed up-and-go test, stair-climbing test, and chair-rising test). Both groups improved knee extension 1RM (24-26 %; p = 0.021), timed up-and-go test (11-16 %; p < 0.001), 6-m walk test (9-12 %; p = 0.004), stair-climbing test (8-13 %; p = 0.007), and chair-rising test (15-16 %; p < 0.001), but there was no significant difference between groups. In conclusion, the strategy of increasing the exposure time at the eccentric phase of movement using the same training volume and intensity does not promote different adaptations in strength or functional capacity compared to conventional resistance training in elderly woman.

Estimation of the efficacy of inertial training in older women

This study aimed to estimate the efficacy of inertial training in older women using the Inertial Training and Measurement System (ITMS), an original device. Forty-five active women age 53-74 yr performed inertial training with 2 different loads (0 or 5 kg) 3 times weekly for 4 wk. Training sessions consisted of exercises involving the shoulder muscles of the dominant and nondominant arms. The maximal torque and power developed by the dominant and nondominant arms in the 0-kg and 5-kg groups were significantly greater after 4 wk of inertial training (with the exception of torque for the nondominant arm in the 5-kg group; p > .05). Thus, short-term training using the ITMS is efficacious and can be used in older women to improve strength and power. However, ITMS training-induced changes in older women are greater after application of smaller external loads.

Reproducibility of velocity-dependent power: before and after lengthening contractions

The determination of power using isokinetic testing has been shown to be highly reliable. However, isotonic and isokinetic testing involve specific mechanical constraints that likely necessitate different neuromuscular strategies. Therefore, the purpose here was to establish test–retest intrarater reliability (separated by 7 days) of loaded maximal shortening velocity and velocity-dependent power of the ankle dorsiflexors using the isotonic mode of the Biodex dynamometer (i) at baseline and (ii) throughout recovery following 150 high-intensity lengthening contractions. Intraclass correlation coefficients (ICC)2,1 with 95% CIs were used to determine relative reliability, whereas absolute reliability included typical error (TEM) and typical error expressed as a coefficient of variation (TEMCV). Twenty-four young men and women volunteered for the study. Maximal shortening velocity and power were determined with a fixed resistance set at 20% of maximal voluntary isometric contraction across 2 testing sessions separated by 7 days. ICCs were 0.93 and 0.98 for maximal shortening velocity and peak power, respectively. Following the lengthening contractions, ICCs indicated high reliability for maximal shortening velocity and peak power, 0.86 and 0.94, respectively, suggesting that a similar amount of fatigue was incurred on both days. Measures of absolute reliability for maximal shortening velocity and peak power also yielded high reliability. The isotonic mode is highly reliable when testing velocity-dependent power of the ankle dorsiflexors at baseline and following fatiguing lengthening contractions. The high reliability of this measure is encouraging and suggests that the isotonic mode can be used in various settings to track group changes before and after training and following fatigue and lengthening contractions.

Neuromuscular contributions to age-related weakness

BACKGROUND

Declines in skeletal muscle mass and quality are important factors contributing to age-related weakness. Neural activation of agonist and antagonist muscles may also be important contributing factors.

METHODS

We conducted a review of the scientific literature on older adults to determine (a) methodologies used to quantify activation, (b) the potential role of agonist and antagonist activation on weakness, and (c) some possible neurophysiological mechanisms that may underlie impaired activation.

RESULTS

The cumulative evidence indicates that agonist activation is impaired in some, but not all, older adults and that this impairment contributes to age-related weakness. It is possible that antagonist coactivation also plays a role in age-related weakness, though a definitive link has not been established.

CONCLUSION

Future research should focus on improving quantitative measurement and mechanistic understanding of impaired activation with aging.

Aging and the force-velocity relationship of muscles

Aging in humans is associated with a loss in neuromuscular function and performance. This is related, in part, to the reduction in muscular strength and power caused by a loss of skeletal muscle mass (sarcopenia) and changes in muscle architecture. Due to these changes, the force-velocity (f-v) relationship of human muscles alters with age. This change has functional implications such as slower walking speeds. Different methods to reverse these changes have been investigated, including traditional resistance training, power training and eccentric (or eccentrically-biased) resistance training. This review will summarise the changes of the f-v relationship with age, the functional implications of these changes and the various methods to reverse or at least partly ameliorate these changes.

Exercise training for patients with cardiovascular disease

This review surveys effort training, a validated and recommended therapy, in patients with atheromatous cardiovascular disease. This true therapy reduces mortality by 25-35%, reduces clinical manifestations and complications (rhythm problems, thrombosis) and improves physical capacity, reintegration and quality of life. The effects are essentially linked to improved metabolic performance of muscles and reduced endothelial dysfunction, insulin resistance and neurohormonal abnormalities. Training also has an impact on the evolution of major risk factors, especially diabetes and arterial hypertension. The risks are limited as long as the contraindications are respected and the programmes supervised. The indications (stable angina, chronic heart failure, peripheral arterial disease) should be described more precisely by taking into account functional criteria: physical deconditioning, exclusion, compliance, mood swings, and seriousness of risk factors. The training programme should be tailor made and based on evaluation of the patient's adaptation to effort, in terms of frequency, intensity and duration of the exercises. Various types of exercise include overall or segmental physical training; concentric, eccentric, even isokinetic muscle contraction exercises; and proprioceptive rehabilitation. However, knowledge is lacking about the molecular mechanisms of the effects of training, the most effective intensity of effort, and strategies to develop physical activity in this ever-growing population for both primary and secondary prevention.

Changes in muscle and joint elasticity following long-term strength training in old age

The current investigation was designed (1) to examine the effect of a 48-week strength training on musculotendinous (MT) and musculoarticular (MA) stiffness characteristics in older men and women; and (2) to evaluate the influence of gender on stiffness behaviour in response to such training. The training was performed twice per week and mainly consisted of three series of 10 repetitions of calf-rise at 75% of the 3-repetition maximum. Two methods were used to perform stiffness measurements during plantar flexion: (1) the use of quick-release movements, allowing the calculation of MT stiffness; (2) the application of sinusoidal perturbations to the joint, allowing the calculation of MA stiffness. In each case, stiffness was linearly related to torque, leading to the calculation of a normalized stiffness index (SI) as the slope of this stiffness-torque relationship: SI(MT) and SI(MA), respectively. Results showed a similar decrease in SI(MT) among older men (-27%, P < 0.05) and women (-29%, P < 0.05) following training. A decrease in SI(MA) was only observed among women (-11%, P < 0.05). The results suggest that (1) MT stiffness decreases following training in older individuals, counterbalancing the effect of ageing; and (2) older men and women respond differently to the same resistance-training stimulus in terms of MA stiffness. Gender-related differences in MA stiffness response may originate from passive MA elastic structures.

Plasticity of dynamic muscle performance with strength training in elderly humans

Data are scarce relating to the plasticity with strength training of dynamic muscle performance in older humans. Hence, we investigated alterations in the torque-velocity relation with strength training in old age, and their origin. Knee extension and leg-press exercises were performed three times per week for 14 weeks. Maximal isokinetic knee extension torque was assessed during concentric and eccentric muscle actions. Agonist-antagonist muscle activation was assessed using electromyography. Vastus lateralis muscle architecture was examined in vivo using ultrasonography. Training increased concentric torque by 22-37% (P < 0.01), but failed to alter eccentric torque (P > 0.05). Increased agonist muscle activation, increased muscle fascicle lengths, and greater elastic energy recovered from tendinous structures may explain the adaptations during concentric actions, whereas the failure of eccentric torque to increase might be explained by the preservation of eccentric force with aging and an underloading of the eccentric movement phase during training. These findings may have important implications for dynamic muscle performance in old age.