Abstract
IntroductionEccentric exercise can reverse age-related decreases in muscle strength and mass; however, no data exist describing its effects on postural sway. As the ankle may be more important for postural sway than hip and knee joints, and with older adults prone to periods of inactivity, the effects of two 6-week seated isokinetic eccentric exercise programmes, and an 8-week detraining period, were examined in 27 older adults (67.1 ± 6.0 years).MethodsNeuromuscular parameters were measured before and after training and detraining periods with subjects assigned to ECC (twice-weekly eccentric-only hip and knee extensor contractions) or ECCPF (identical training with additional eccentric-only plantarflexor contractions) training programmes.ResultsSignificant (P < 0.05) increases in mobility (decreased timed-up-and-go time [− 7.7 to − 12.0%]), eccentric strength (39.4–58.8%) and vastus lateralis thickness (9.8–9.9%) occurred after both training programmes, with low-to-moderate weekly rate of perceived exertion (3.3–4.5/10) reported. No significant change in any postural sway metric occurred after either training programme. After 8 weeks of detraining, mobility (− 8.2 to − 11.3%), eccentric strength (30.5–50.4%) and vastus lateralis thickness (6.1–7.1%) remained significantly greater than baseline in both groups.ConclusionDespite improvements in functional mobility, muscle strength and size, lower-limb eccentric training targeting hip, knee and ankle extensor muscle groups was not sufficient to influence static balance. Nonetheless, as the beneficial functional and structural adaptations were largely maintained through an 8-week detraining period, these findings have important implications for clinical exercise prescription as the exercise modality, low perceived training intensity, and adaptive profile are well suited to the needs of older adults.
Highlights
Eccentric exercise can reverse age-related decreases in muscle strength and mass; no data exist describing its effects on postural sway
We hypothesised that both isokinetic eccentric resistance training programmes would significantly reduce TUG time and increase muscle strength, thickness and architecture, and that the positive effects of training would be largely retained at 8 weeks following the cessation of training
We hypothesised that postural sway would be significantly reduced only in the ECCPF group
Summary
Eccentric exercise can reverse age-related decreases in muscle strength and mass; no data exist describing its effects on postural sway. Whilst a range of exercise interventions have been demonstrated to reverse age-related reductions in physical function (Chou et al 2012), limited cardiorespiratory capacity, locomotor ability, and fear of falling can reduce exercise capacity and tolerance (LaStayo et al 2003) These issues can subsequently limit the ability to exercise at a sufficient intensity to prevent further losses in neuromuscular function, accelerating decline and contributing to the development of frailty (Cesari et al 2014), increased levels of disability (Freedman et al 2002), and poor quality of life (Chou et al 2012). Seated resistance exercise (e.g. performed on isokinetic machines) can be used in populations with poor mobility or fear of falling, whilst allowing for an adequate stimulus to be provided for lower-limb muscle strength improvement, as previously demonstrated in both young adult (Kay et al 2018) and older (LaStayo et al 2003)
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