Effects of detraining on neuromuscular function and structural adaptations following once- or twice-weekly eccentric resistance training in older adults.

BACKGROUND: Eccentric resistance training elicits greater preservation of training-induced muscular adaptations compared with other training modalities, however the detraining profiles of different training dosages remain unknown. AIMS: To examine the detraining effects following once- or twice-weekly eccentric-specific resistance training in older adults. METHODS: Twenty-one older adults (age = 70.5 ± 6.0 year) completed a 12-week detraining period following the 12-week eccentric training programmes with neuromuscular function and muscle structure assessed six (mid-detraining) and 12 (post-detraining) weeks following training cessation. RESULTS: From post-training to post-detraining, no significant regression of the training-induced improvements (collapsed group data reported) occurred in power (0%), strength (eccentric = 0%, isometric = 39%), or explosive strength over numerous epochs (0-32%), resulting in values that remained significantly greater than at pre-training. However, significant regression in the improvements in muscle thickness (91%) and fascicle angle (100%) occurred, resulting in values that were not significantly greater than pre-training. DISCUSSION: The limited regression in neuromuscular function following a 12-week detraining period has important implications for supporting eccentric exercise prescription in older adults who often face periods of inactivity. However, further work is required to develop an effective maintenance dosage strategy that preserves improvements in muscle structure. CONCLUSIONS: Eccentric resistance training elicits improvements in the neuromuscular function of older adults, which are sustained for at least 12 weeks after eccentric training cessation.

Effects of once- versus twice-weekly eccentric resistance training on muscular function and structure in older adults: a randomised controlled trial.

Adherence rates to current twice-weekly strength training guidelines are poor among older adults. Eccentric-only training elicits substantial improvements in muscle function/size so the aim of this study was to compare the effects of once- versus twice-weekly eccentric training programmes on muscle function/size in older adults. Thirty-six participants (69.4 ± 6.0 yr) were randomised into non-active control, once-, or twice-weekly training groups. Lower-limb muscle power, strength, and size were assessed at baseline, mid-, and post-eccentric training. Training was performed for 12 min per session at 50% of maximum eccentric strength. Significant increases in power (13%), isometric (17-36%) and eccentric (40-50%) strength, and VL muscle thickness (9-18%) occurred in both training groups following 12 weeks. Minimal muscle soreness was induced throughout the 12 weeks and perceived exertion was consistently lower in the twice-weekly training group. One weekly submaximal eccentric resistance training session over 12 weeks elicits similar improvements in neuromuscular function compared to the currently recommended twice-weekly training dose. Given the substantial improvements in neuromuscular function and previously reported low adherence to current twice-weekly training guidelines, eccentric training may be pivotal to developing a minimal-dose strategy to counteract neuromuscular decline. The trial was registered retrospectively on 24/01/2024 with ISRCTN (trial registration number: ISRCTN68730580).

The acute and repeated bout effects of multi-joint eccentric exercise on physical function and balance in older adults.

PURPOSE: Eccentric muscle actions generate high levels of force at a low metabolic cost, making them a suitable training modality to combat age-related neuromuscular decline. The temporary muscle soreness associated with high intensity eccentric contractions may explain their limited use in clinical exercise prescription, however any discomfort is often alleviated after the initial bout (repeated bout effect). Therefore, the aims of the present study were to examine the acute and repeated bout effects of eccentric contractions on neuromuscular factors associated with the risk of falling in older adults. METHODS: Balance, functional ability [timed up-and-go and sit-to-stand], and lower-limb maximal and explosive strength were measured in 13 participants (67.6 ± 4.9 year) pre- and post-eccentric exercise (0, 24, 48, and 72 hr) in Bout 1 and 14 days later in Bout 2. The eccentric exercise intervention was performed on an isokinetic unilateral stepper ergometer at 50% of maximal eccentric strength at 18 step‧min-1 per limb for 7 min (126 steps per limb). Two-way repeated measures ANOVAs were conducted to identify any significant effects (P ≤ 0.05). RESULTS: Eccentric strength significantly decreased (- 13%) in Bout 1 at 24 hr post-exercise; no significant reduction was observed at any other time-point after Bout 1. No significant reductions occurred in static balance or functional ability at any time-point in either bout. CONCLUSION: Submaximal multi-joint eccentric exercise results in minimal disruption to neuromuscular function associated with falls in older adults after the initial bout.

The Comparative Effect of Different Timings of Whole Body Cryotherapy Treatment With Cold Water Immersion for Post-Exercise Recovery.

Despite several established benefits of Whole Body Cryotherapy (WBC) for post-exercise recovery, there is a scarcity of research which has identified the optimum WBC protocol for this purpose. This study investigated the influence of WBC treatment timing on physiological and functional responses following a downhill running bout. An additional purpose was to compare such responses with those following cold water immersion (CWI), since there is no clear consensus as to which cold modality is more effective for supporting athletic recovery. Thirty-three male participants (mean ± SD age 37.0 ± 13.3 years, height 1.76 ± 0.07 m, body mass 79.5 ± 13.7 kg) completed a 30 min downhill run (15% gradient) at 60% VO2 max and were then allocated into one of four recovery groups: WBC1 (n = 9) and WBC4 (n = 8) underwent cryotherapy (3 min, -120°C) 1 and 4 h post-run, respectively; CWI (n = 8) participants were immersed in cold water (10 min, 15°C) up to the waist 1 h post-run and control (CON, n = 8) participants passively recovered in a controlled environment (20°C). Maximal isometric leg muscle torque was assessed pre and 24 h post-run. Blood creatine kinase (CK), muscle soreness, femoral artery blood flow, plasma IL-6 and sleep were also assessed pre and post-treatment. There were significant decreases in muscle torque for WBC4 (10.9%, p = 0.04) and CON (11.3% p = 0.00) and no significant decreases for WBC1 (5.6%, p = 0.06) and CWI (5.1%, p = 0.15). There were no significant differences between groups in muscle soreness, CK, IL-6 or sleep. Femoral artery blood flow significantly decreased in CWI (p = 0.02), but did not differ in other groups. WBC treatments within an hour may be preferable for muscle strength recovery compared to delayed treatments; however WBC appears to be no more effective than CWI. Neither cold intervention had an impact on inflammation or sleep.

The Effect of Repetitive Whole Body Cryotherapy Treatment on Adaptations to a Strength and Endurance Training Programme in Physically Active Males.

Despite its potential merit in sport and exercise recovery, the implications of repetitive Whole Body Cryotherapy (WBC) during training programmes require further review due to the possibility of repetitive cold interfering with long term adaptations. This study investigated the impact of two weekly 3 min WBC sessions (30 s at -60°C, 150 s at -120°C) on adaptations to a 6 week strength and endurance training programme. Sixteen male participants (mean ± SD age 33.4 ± 9.8 years, body mass 82.3 ± 9.8 kg) randomly allocated into WBC (n = 7) and non-cryotherapy control (CON, n=9) groups completed the programme consisting of two weekly strength and plyometric training sessions and two weekly 30 min runs (70% VO2 max). Participants were assessed for body fat, VO2 max, muscle torque, three repetition maximum barbell squat and countermovement jump height before and after the programme. Resistance and running intensities were progressed after 3 weeks. Participants in both groups significantly improved muscle torque (WBC: 277.1 ± 63.2 Nm vs. 318.1 ± 83.4 Nm, p < 0.01, d = 0.56; CON: 244.6 ± 50.6 Nm vs. 268.0 ± 71.8 Nm, p = 0.05, d = 0.38) and barbell squat (WBC: 86.4 ± 19.5 kg vs. 98.9 ± 15.2 kg, p = 0.03, d = 0.69; CON: 91.1 ± 28.7 kg vs. 106.1 ± 30.0 kg, p < 0.01, d=0.51) following the 6 week programme. For the CON group, there was also a significant reduction in body fat percentage (p = 0.01) and significant increase in jump height (p = 0.01). There was no significant increase in VO2 max for either group (both p > 0.2). There was no difference between WBC and CON for responses in muscle torque, 3RM barbell squat and body fat, however WBC participants did not increase their jump height (p = 0.23). Repetitive WBC does not appear to blunt adaptations to a concurrent training programme, although there may be an interference effect in the development of explosive power. Sports practitioners can cautiously apply repetitive WBC to support recovery post-exercise without undue concern on athletes' fitness gains or long term performance, particularly throughout training phases focused more on general strength development than explosive power.

Effects of isometric leg training on ambulatory blood pressure and morning blood pressure surge in young normotensive men and women.

Despite the reported association between diurnal variations in ambulatory blood pressure (BP) and elevated cardiovascular disease risk, little is known regarding the effects of isometric resistance training (IRT), a practical BP-lowering intervention, on ambulatory BP and morning BP surge (MBPS). Thus, we investigated whether (i) IRT causes reductions in ambulatory BP and MBPS, in young normotensives, and (ii) if there are any sex differences in these changes. Twenty normotensive individuals (mean 24-h SBP = 121 ± 7, DBP = 67 ± 6 mmHg) undertook 10-weeks of bilateral-leg IRT (4 × 2-min/2-min rest, at 20% maximum voluntary contraction (MVC) 3 days/week). Ambulatory BP and MBPS (mean systolic BP (SBP) 2 h after waking minus the lowest sleeping 1 h mean SBP) was measures pre- and post-training. There were significant reductions in 24-h ambulatory SBP in men (- 4 ± 2 mmHg, P = 0.0001) and women (- 4 ± 2 mmHg, P = 0.0001) following IRT. Significant reductions were also observed in MBPS (- 6 ± 8 mmHg, p = 0.044; - 6 ± 7 mmHg, P = 0.019), yet there were no significant differences between men and women in these changes, and 24-h ambulatory diastolic BP remained unchanged. Furthermore, a significant correlation was identified between the magnitude of the change in MBPS and the magnitude of changes in the mean 2-h SBP after waking for both men and women (men, r = 0.89, P = 0.001; women, r = 0.74, P = 0.014). These findings add further support to the idea that IRT, as practical lifestyle intervention, is effective in significantly lowering ambulatory SBP and MBPS and might reduce the incidence of adverse cardiovascular events that often occur in the morning.

The Effects of Age and Body Fat Content on Post-Downhill Run Recovery Following Whole Body Cryotherapy.

This study explored the effects of age and body fat content on responses to whole body cryotherapy (WBC) following a downhill running bout. Forty-one male participants (mean ± SD age 42.0 ± 13.7 years, body mass 75.2 ± 10.8 kg) were allocated into WBC (n = 26) and control (CON, n = 15) groups. WBC participants were divided into old (OLD, ≥45 years, n = 10) and young (YNG, <40 years, n = 13), as well as high fat (HFAT, ≥20%, n = 10) and low fat (LFAT ≤ 15%, n = 8) groups. Participants completed a 30 min downhill run (15% gradient) at 60% VO2 max. The WBC group underwent cryotherapy (3 min, -120 °C) 1 h post-run and CON participants passively recovered in a controlled environment (20 °C). Maximal isometric leg muscle torque was assessed pre and 24 h post-run. Blood creatine kinase (CK) and muscle soreness were assessed pre, post, one hour and 24 h post-run. Muscle torque significantly decreased in both groups post-downhill run (WBC: 220.6 ± 61.4 Nm vs. 208.3 ± 67.6 Nm, p = 0.02; CON: 239.7 ± 51.1 Nm vs. 212.1 ± 46.3 Nm, p = 0.00). The mean decrease in WBC was significantly less than in CON (p = 0.04). Soreness and CK increased 24 h post for WBC and CON (p < 0.01) with no difference between groups. Muscle torque significantly decreased in OLD participants (p = 0.04) but not in YNG (p = 0.55). There were no differences between HFAT and LFAT (all p values > 0.05). WBC may attenuate muscle damage and benefit muscle strength recovery following eccentrically biased exercises, particularly for young males.

Acute Response to a 2-Minute Isometric Exercise Test Predicts the Blood Pressure-Lowering Efficacy of Isometric Resistance Training in Young Adults.

BACKGROUND: This work aimed to explore whether different forms of a simple isometric exercise test could be used to predict the blood pressure (BP)-lowering efficacy of different types of isometric resistance training (IRT) in healthy young adults. In light of the emphasis on primary prevention of hypertension, identifying those with normal BP who will respond to IRT is important. Also, heightened BP reactivity increases hypertension risk, and as IRT reduces BP reactivity in patients with hypertension, it warrants further investigation in a healthy population. METHODS: Forty-six young men and women (24 ± 5 years; 116 ± 10/ 68 ± 8 mm Hg) were recruited from 2 study sites: Windsor, Canada (n = 26; 13 women), and Northampton, United Kingdom (n = 20; 10 women). Resting BP and BP reactivity to an isometric exercise test were assessed prior to and following 10 weeks of thrice weekly IRT. Canadian participants trained on a handgrip dynamometer (isometric handgrip, IHG), while participants in the UK trained on an isometric leg extension dynamometer (ILE). RESULTS: Men and women enrolled in both interventions demonstrated significant reductions in systolic BP (P < 0.001) and pulse pressure (P < 0.05). Additionally, test-induced systolic BP changes to IHG and ILE tests were associated with IHG and ILE training-induced reductions in systolic BP after 10 weeks of training, respectively (r = 0.58 and r = 0.77; for IHG and ILE; P < 0.05). CONCLUSIONS: The acute BP response to an isometric exercise test appears to be a viable tool to identify individuals who may respond to traditional IRT prescription.

Reductions in Resting Blood Pressure in Young Adults When Isometric Exercise Is Performed Whilst Walking.

Aerobic and isometric training have been shown to reduce resting blood pressure, but simultaneous aerobic and isometric training have not been studied. The purpose of this study was to compare the changes in resting systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MAP) after 6 weeks of either (i) simultaneous walking and isometric handgrip exercise (WHG), (ii) walking (WLK), (iii) isometric handgrip exercise (IHG), or control (CON). Forty-eight healthy sedentary participants (age 20.7 ± 1.7 yrs, mass 67.2 ± 10.2 kg, height 176.7 ± 1.2 cm, male n = 26, and female n = 22) were randomly allocated, to one of four groups (n = 12 in each). Training was performed 4 × week-1 and involved either treadmill walking for 30 minutes (WLK), handgrip exercise 3 × 10 s at 20% MVC (IHG), or both performed simultaneously (WHG). Resting SBP, DBP, and MAP were recorded at rest, before and after the 6-week study period. Reductions in resting blood pressure were significantly greater in the simultaneous walking and handgrip group than any other group. These results show that simultaneous walking and handgrip training may have summative effects on reductions in resting blood pressure.

Double-leg isometric exercise training in older men.

Double-leg isometric training has been demonstrated to reduce resting blood pressure in young men when using electromyographic activity (EMG) to regulate exercise intensity. This study assessed this training method in healthy older (45-60 years.) men. Initially, 35 older men performed an incremental isometric exercise test to determine the linearity of the heart rate versus percentage peak EMG (%EMGpeak) and systolic blood pressure versus %EMGpeak relationship. Thereafter, 20 participants were allocated to a training or control group. The training group performed three double-leg isometric sessions per week for 8 weeks, at 85% of peak heart rate. The training resulted in a significant reduction in resting systolic (11 ± 8 mmHg, P < 0.05) and mean arterial (5 ± 7 mmHg, P < 0.05) blood pressure. There was no significant change in resting systolic blood pressure for the control group or diastolic blood pressure in either group (all P > 0.05). These findings show that this training method, used previously in young men, is also effective in reducing resting systolic and mean arterial blood pressure in older men.

Effects of the intensity of leg isometric training on the vasculature of trained and untrained limbs and resting blood pressure in middle-aged men.

The purpose of this study was to establish whether changes in resting blood pressure and the vasculature of trained and untrained limbs are dependent on training intensity, following isometric-leg training. Thirty middle-aged males undertook an 8 week training programme (4 × 2 min bilateral-leg isometric contractions 3 times per week). Two groups trained at either high (HI; 14%MVC) or low (LO; 8%MVC) intensity a third group (CON) acted as controls. All parameters were measured at baseline, 4-weeks and post-training. Resting SBP (-10.8 ± 7.9 mmHg), MAP (-4.7 ± 6.8 mmHg) and HR (-4.8 ± 5.9 b·min(-1)) fell significantly in the HI group post-training with concomitant significant increases in resting femoral mean artery diameter (FMAD; 1.0 ± 0.4 mm), femoral mean blood velocity (FMBV; 0.68 ± 0.83 cm·s(-1)), resting femoral artery blood flow (FABF; 82.06 ± 31.92 ml·min(-1)) and resting femoral vascular conductance (FVC, 45%). No significant changes occurred in any brachial artery measure nor in any parameters measured in the LO or CON groups. These findings show that training-induced reductions in resting blood pressure after isometric-leg training in healthy middle-aged men are associated with concomitant adaptations in the local vasculature, that appear to be dependent on training intensity and take place in the later stages of training.