Age, Isometric Strength, Rate of Tension Development and Fiber Type Composition

Clarkson, Priscilla M.; Kroll, Walter; Melchionda, Anthony M.

doi:10.1093/geronj/36.6.648

Cited by 78 publications

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“…After 4 months of detraining, however, younger patients maintained more of their strength probably because they were more active during the detraining period. This is in agreement with other studies [24,25,26]. Data from our laboratory, using a different mode of exercise, showed that 3 months of detraining were sufficient to reverse the induced muscular strength obtained after systematic land training of 8 months [15].…”

Section: Discussionsupporting

confidence: 93%

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Training, Detraining and Retraining Effects after a Water-Based Exercise Program in Patients with Coronary Artery Disease

Tokmakidis

Spassis

Volaklis³

2008

Cardiology

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Objective: The aim of this study was to investigate the adaptations of a water-based training program as well as the detraining and retraining effects on physiological parameters in patients with coronary artery disease (CAD). Methods: Twenty-one patients were separated in an exercise group (n = 11) and a control group (n = 10). The exercise group followed three periods: training, detraining and retraining. Each period lasted 4 months. During the training and the retraining periods, the patients performed four sessions of water exercise (not swimming) per week. Results: The water-based program was well-accepted and no adverse effects were observed. The exercise group improved (p < 0.05) their stress-test time (+11.8%), VO_{2 peak} (+8.4%) and total body strength (+12.2%) after the training period; detraining tended to reverse these positive adaptations. Resumption of training increased the beneficial effects obtained after the initial training period (exercise stress: +4.5%; VO_{2 peak}: +6.6%; total strength: +7.0%). The patients in the control group did not show any significant alterations throughout the study. Conclusion: Water-based exercise is safe and induces positive physiological and muscular adaptations in low-risk patients with CAD. These could be reversed, however, after the cessation of exercise. This is why uninterrupted exercise throughout life is a must.

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Section: Discussionsupporting

confidence: 93%

“…The reduction of strength was more remarkable in patients who were stronger before the cessation of water-based exercise, and this varied from one muscle group to the other [24, 25]. Higher reduction in the strength of leg flexors (hamstring curl, –7.1%) was observed in our patients.…”

Section: Discussionmentioning

confidence: 66%

Training, Detraining and Retraining Effects after a Water-Based Exercise Program in Patients with Coronary Artery Disease

Tokmakidis

Spassis

Volaklis³

2008

Cardiology

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“…In healthy elderly individuals, it has been demonstrated that the ability to develop force rapidly (i.e., contractile RFD) is reduced compared with that in young individuals of both genders (5,42), likely due to the decreased number and size of type II muscle fibers in the elderly (29) and an increased amount of noncontractile intramuscular tissue (29). However, when RFD is normalized relative to MVC, a difference between young and old subjects is not a universal finding (5,40). In the present study, absolute contractile RFD was lower on AF compared with UN in both men (ϳ18%) and women (ϳ25%).…”

Section: Discussionmentioning

confidence: 99%

“…Reduced contractile RFD has been demonstrated in elderly compared with young individuals of both genders (5,42). However, to what extent reductions in muscle mass or size, suppression in voluntary muscle activation, elevated coactivation of antagonist muscles, or a general reduction in the physical activity level is responsible for the decrease in muscle strength in the elderly remains unclear.…”

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confidence: 99%

Muscle size, neuromuscular activation, and rapid force characteristics in elderly men and women: effects of unilateral long-term disuse due to hip-osteoarthritis

Suetta¹,

Aagaard²,

Magnusson³

et al. 2007

Journal of Applied Physiology

142

128

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Suetta C, Aagaard P, Magnusson SP, Andersen LL, Sipilä S, Rosted A, Jakobsen AK, Duus B, Kjaer M. Muscle size, neuromuscular activation, and rapid force characteristics in elderly men and women: effects of unilateral long-term disuse due to hip-osteoarthritis. J Appl Physiol 102: [942][943][944][945][946][947][948] 2007. First published November 22, 2006; doi:10.1152/japplphysiol.00067.2006.-Substantial evidence exists for the age-related decline in muscle strength and neural function, but the effect of long-term disuse in the elderly is largely unexplored. The present study examined the effect of unilateral long-term limb disuse on maximal voluntary quadriceps contraction (MVC), lean quadriceps muscle cross-sectional area (LCSA), contractile rate of force development (RFD, ⌬force/⌬time), impulse (͐force dt), muscle activation deficit (interpolated twitch technique), maximal neuromuscular activity [electromyogram (EMG)], and antagonist muscle coactivation in elderly men (M: 60 -86 yr; n ϭ 19) and women (W: 60 -86 yr; n ϭ 20) with unilateral chronic hip-osteoarthritis. Both sides were examined to compare the effect of long-term decreased activity on the affected (AF) leg with the unaffected (UN) side. AF had a significant lower MVC (W: 20%; M: 20%), LCSA (W: 8%; M: 10%), contractile RFD (W: 17-26%; M: 15-24%), impulse (W: 10 -19%, M: 19 -20%), maximal EMG amplitude (W: 22-25%, M: 22-28%), and an increased muscle activation deficit (Ϫ18%) compared with UN. Furthermore, women were less strong (AF: 40%; UN: 39%), had less muscle mass (AF: 33%; UN: 34%), and had a lower RFD (AF: 38 -50%; UN: 41-48%) compared with men. Similarly, maximum EMG amplitude was smaller for both agonists (AF: 51-63%; UN: 35-61%) and antagonist (AF: 49 -64%; UN: 36 -56%) muscles in women compared with men. However, when MVC and RFD were normalized to LCSA, there were no differences between genders. The present data demonstrate that disuse leads to a marked loss of muscle strength and muscle mass in elderly individuals. Furthermore, the data indicate that neuromuscular activation and contractile RFD are more affected by long-term disuse than maximal muscle strength, which may increase the future risk for falls.aging; rate of force development; neural activity; muscle activation IT IS WELL KNOWN FROM ANIMAL and human studies that a chronic reduction in neuromuscular activity results in marked muscle atrophy (4, 28), reduced muscle strength (2, 33), and diminished neural drive to muscle fibers (9). For people older than 45 yr of age, Ͼ33% suffer from joint pain, and osteoarthritis (OA) has been shown to be the most common cause of inactivity and long-term disability in people aged Ն65 yr (12). However, most of the current knowledge with respect to the effects of inactivity and immobilization on neuromuscular function is based on animal data (2, 8) or on studies performed on healthy young individuals (4, 28). This is contrasted by the fact that the elderly population more often undergoes periods of immobilization and disuse, not only due to join...

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“…It has also been shown that there is a decrease in membrane excitability of muscle fibers and decreased efficiency of the Na ϩ /K ϩ pump in muscle fibers (De Luca et al 1990;Hicks et al 1992;Klitgaard and Clausen 1989). Any combination of these changes may make doublet discharges less likely to occur in the aging neuromuscular system, which could contribute to the decrease in muscular force production with age that has been well documented (Backman et al 1995;Clarkson et al 1981;Kent-Braun and Ng 1999). Alternatively, the aging neuromuscular system may maintain, or even increase the occurrence of doublet discharges, to compensate for decreased maximal motor unit firing rates.…”

Section: Introductionmentioning

confidence: 99%

Doublet Discharges in Motoneurons of Young and Older Adults

Christie

Kamen²

2006

Journal of Neurophysiology

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Christie, Anita and Gary Kamen. Doublet discharges in motoneurons of young and older adults. J Neurophysiol 95: 2787-2795, 2006. First published February 1, 2006 doi:10.1152/jn.00685.2005. The purpose of this study was to investigate the occurrence of motor unit doublet discharges in young and older individuals at different rates of increasing force. Participants included eight young (21.9 Ϯ 3.56 yr) and eight older (74.1 Ϯ 8.79 yr) individuals, with equal numbers of males and females in each group. Motor unit activity was recorded from the tibialis anterior during isometric dorsiflexion using a fourwire needle electrode. Subjects performed three ramp contractions from zero to 50% maximal voluntary contraction (MVC) force at each of three rates: 10, 30, and 50% MVC/s. Overall, the occurrence of doublets was significantly higher in the young than in the older individuals. However, neither group showed differences in the occurrence of doublets across the three rates of force production. Doublet firings were observed in 45.6 (young) and 35.1% (old) of motor units at 10% MVC/s; 48.6 (young) and 22.5% (old) of motor units at 30% MVC/s; and 48.4 (young) and 31.4% (old) at 50% MVC/s. The maximal firing rate was significantly higher and the force at which the motor units were recruited was significantly lower for those units that fired doublets than those that did not. The force at which doublets occurred ranged from 3.42 to 50% MVC in the young subjects and from 0 (force onset) to 50% MVC in the older subjects. The results of this study suggest that the occurrence of doublets is dependent on both motor unit firing rate and force level. The lower incidence of doublets in older individuals may be attributable to changes in the intrinsic properties of the motoneurons with aging, which appear to play a role in doublet discharges.

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Age, Isometric Strength, Rate of Tension Development and Fiber Type Composition

Cited by 78 publications

References 0 publications

Training, Detraining and Retraining Effects after a Water-Based Exercise Program in Patients with Coronary Artery Disease

Training, Detraining and Retraining Effects after a Water-Based Exercise Program in Patients with Coronary Artery Disease

Muscle size, neuromuscular activation, and rapid force characteristics in elderly men and women: effects of unilateral long-term disuse due to hip-osteoarthritis

Doublet Discharges in Motoneurons of Young and Older Adults

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