Objectives
To assess whether resistance training (RT) slows the progression of white matter lesions (WMLs) in older women.
Design
Secondary analysis of a 52‐week randomized controlled trial of RT, ...the Brain Power Study.
Setting
Community center and research center.
Participants
Of 155 community‐dwelling women aged 65 to 75 enrolled in the Brain Power Study, 54 who had evidence of WMLs on magnetic resonance imaging (MRI) at baseline were included in this secondary analysis.
Intervention
Participants were randomized to once‐weekly RT (1× RT), twice‐weekly RT (2× RT), or twice‐weekly balance and tone (BAT). Assessors were blinded to participant assignments.
Measurements
WML volume was measured using MRI at baseline and trial completion.
Results
At trial completion, the 2× RT group had significantly lower WML volume than the BAT group (P = .03). There was no significant difference between the BAT group and the 1× RT group at trial completion (P = .77). Among participants in the two RT groups, reduced WML progression over 12 months was significantly associated with maintenance of gait speed (correlation coefficient (r) = −0.31, P = .049) but not with executive functions (r = 0.30; P = .06).
Conclusion
Engaging in progressive RT may reduce WML progression.
Sled pushing is a commonly used form of resisted sprint training; however, little empirical evidence exists, especially in youth populations. The aim of this study was to assess the effectiveness of ...unresisted and resisted sled pushing across multiple loads. Fifty high school athletes were assigned to an unresisted (n = 12), or 3 resisted groups; light (n = 14), moderate (n = 13), and heavy (n = 11) resistance that caused a 25%, 50%, and 75% velocity decrement in maximum sprint speed, respectively. All participants performed two sled‐push training sessions twice weekly for 8 weeks. Before and after the training intervention, the participants performed a series of jump, strength, and sprint testing to assess athletic performance. Split times between 5 and 20 m improved significantly across all resisted groups (all P < .05, d = 0.34‐1.16) but did not improve significantly with unresisted sprinting. For all resisted groups, gains were greatest over the first 5 m (d = 0.67‐0.84) and then diminished over each subsequent 5 m split (d = 0.08‐0.57). The magnitude of gains in split times was greatest within the heavy group. Small but non‐significant within‐group effects were found in pre to post force‐velocity profiles. There was a main effect of time but no interaction effects as all groups increased force and power, although the greatest increases were observed with the heavy load (d = 0.50‐0.51). The results of this study suggest that resisted sled pushing with any load was superior to unresisted sprint training and that heavy loads may elicit the greatest gains in sprint performance over short distances.
Objective: Individuals with neurological damage (e.g., stroke or cerebral palsy) often experience a significant loss of arm function. Robotic devices that address muscle strength deficits in a ...task-specific manner can assist in the recovery of arm function; however, current devices are typically large, bulky, and expensive to be routinely used in the clinic or at home. This study sought to address this issue by developing a portable planar passive rehabilitation robot, PaRRo. Methods: We designed PaRRo with a mechanical layout that incorporated kinematic redundancies to generate forces that directly oppose the user's movement. Cost-efficient eddy current brakes were used to provide scalable resistances. The lengths of the robots linkages were optimized to have a reasonably large workspace for human planar reaching. We then performed theoretical analysis of the robot's resistive force generating capacity and steerable workspace using MATLAB simulations. We also validated a prototype device by having a subject move the end-effector along different paths at a set velocity using a metronome while simultaneously collecting surface electromyography (EMG) and end-effector forces felt by the user. Results: Results from simulation experiments indicated that the robot was capable of producing sufficient end-effector forces for functional resistance training. We also found the end-effector forces from the user were similar to the theoretical forces expected at any direction of motion. EMG results indicated that the device was capable of providing adjustable resistances based on subjects' ability levels, as the muscle activation levels scaled with increasing magnet exposures. Conclusion: These results indicate that PaRRo is a feasible approach to provide functional resistance training to the muscles along the upper-extremity. Significance: The proposed robotic device could provide a technological breakthrough that will make rehabilitation robots accessible for small outpatient rehabilitation centers and in-home therapy.
PURPOSEThis study aimed to compare the effects of four resistance training (RT) programs with different velocity loss (VL) thresholds0% (VL0), 10% (VL10), 20% (VL20), and 40% (VL40) on sprint and ...jump performance, muscle strength, neuromuscular, muscle hypertrophy, and architectural adaptations.
METHODSSixty-four young resistance-trained men were randomly assigned into four groups (VL0, VL10, VL20, and VL40) that differed in the VL allowed in each set. Subjects followed an RT program for 8 wk (two sessions per week) using the full-squat (SQ) exercise, with similar relative intensity (70%–85% 1-repetition maximum), number of sets (3), and interset recovery period (4 min). Before and after the RT program, the following tests were performed1) muscle hypertrophy and architecture of the vastus lateralis (VLA), 2) tensiomyography, 3) 20-m running sprint, 4) vertical jump, 5) maximal voluntary isometric contraction in SQ, 6) progressive loading test in SQ, and 7) fatigue test.
RESULTSNo between-group differences existed for RT-induced gains in sprint, jump, and strength performance despite the differences in the total volume performed by each group. VL20 and VL40 showed significant increases (P < 0.001) in muscle hypertrophy (group–time interaction, P = 0.06). However, only VL40 exhibited a significant slowing (P < 0.001) of the delay time in the VLA muscle (group–time interaction, P = 0.05). Moreover, VL40 showed a significant decrease in the early rate of force development (P = 0.04).
CONCLUSIONSHigher VL thresholds (i.e., VL20 and VL40) maximized hypertrophic adaptations, although an excessive VL during the set (i.e., VL40) may also induce negative neuromuscular adaptations. Therefore, moderate VL thresholds should be chosen to maximize strength adaptations and to prevent negative neuromuscular adaptations.
Purpose
This study aimed to explore the feasibility of vertical force–velocity (F–V) profiles to monitor changes in muscle function following different fatigue protocols. The between-day reliability ...of vertical F–V profiles and the acute effects of two fatigue protocols on the changes of lower limb muscle function were examined.
Methods
Twelve resistance trained males completed a preliminary session to determine their back squat one-repetition maximum (1RM). Afterwards, they randomly performed two experimental sessions that only differed in the fatigue protocol applied: heavy-load traditional (HLT; five repetitions at 80% 1RM) and light-load ballistic (LLB; five repetitions at 30% 1RM) squat protocols. Participants’ vertical F–V profiles (maximum theoretical force
F
0
, maximum theoretical velocity
v
0
, and maximum power output
P
max
) were calculated before and immediately after each fatigue protocol.
Results
F
0
,
v
0
, and
P
max
showed acceptable to good between-day reliability (coefficient of variation ≤ 4.4%; intraclass correlation coefficient ≥ 0.84). Both fatigue protocols promoted a comparable reduction in
P
max
(−10.1% for HLT and −12.2% for LLB). However, the LLB squat protocol reduced more
v
0
(−9.7%) than
F
0
(−0.4%), while the HLT squat protocol reduced
F
0
(−8.4%) more than
v
0
(−4.1%).
Conclusions
The vertical F–V profile can be used to monitor changes in muscle function given its acceptable between-day reliability and its high sensitivity to detect the acute effect of force-oriented and velocity-oriented fatigue protocols on specific maximal neuromuscular capacities.
It is well documented that both balance and resistance training have the potential to mitigate intrinsic fall risk factors in older adults. However, knowledge about the effects of simultaneously ...executed balance and resistance training (i.e., resistance training conducted on unstable surfaces URT) on lower-extremity muscle strength, power and balance in older adults is insufficient. The objective of the present study was to compare the effects of machine-based stable resistance training (M-SRT) and two types of URT, i.e., machine-based (M-URT) and free-weight URT (F-URT), on measures of lower-extremity muscle strength, power and balance in older adults.
Seventy-five healthy community-dwelling older adults aged 65-80 years, were assigned to three intervention groups: M-SRT, M-URT and F-URT. Over a period of ten weeks, all participants exercised two times per week with each session lasting ~60 min. Tests included assessment of leg muscle strength (e.g., maximal isometric leg extension strength), power (e.g., chair rise test) and balance (e.g., functional reach test), carried out before and after the training period. Furthermore, maximal training load of the squat-movement was assessed during the last training week.
Maximal training load of the squat-movement was significantly lower in F-URT in comparison to M-SRT and M-URT. However, lower-extremity resistance training conducted on even and uneven surfaces meaningfully improved proxies of strength, power and balance in all groups. M-URT produced the greatest improvements in leg extension strength and F-URT in the chair rise test and functional reach test.
Aside from two interaction effects, overall improvements in measures of lower-extremity muscle strength, power and balance were similar across training groups. Importantly, F-URT produced similar results with considerably lower training load as compared to M-SRT and M-URT. Concluding, F-URT seems an effective and safe alternative training program to mitigate intrinsic fall risk factors in older adults.
This trial has been registered with clinicaltrials.gov ( NCT02555033 ) on 09/18/2015.
To examine the effects of short-term, medium-term and long-term resistance exercise training (RET) on measures of cardiometabolic health in adults.
Intervention systematic review.
MEDLINE and ...Cochrane Library databases were searched from inception to February 2018. The search strategy included the following keywords: resistance exercise, strength training and randomised controlled trial.
Randomised controlled trials published in English comparing RET≥2 weeks in duration with a non-exercising control or usual care group. Participants were non-athletic and aged ≥18 years.
A total of 173 trials were included. Medium-term and long-term RET reduced systolic blood pressure (-4.02 (95% CI -5.92 to -2.11) mm Hg, p<0.0001 and -5.08 (-10.04 to -0.13) mm Hg, p=0.04, respectively) and diastolic blood pressure (-1.73 (-2.88 to -0.57) mm Hg, p=0.003 and -4.93 (-8.58 to -1.28) mm Hg, p=0.008, respectively) versus control. Medium-term RET elicited reductions in fasted insulin and insulin resistance (-0.59 (-0.97 to -0.21) µU/mL, p=0.002 and -1.22 (-2.29 to -0.15) µU/mL, p=0.02, respectively). The effects were greater in those with elevated cardiometabolic risk or disease compared with younger healthy adults. The quality of evidence was low or very low for all outcomes. There was limited evidence of adverse events.
RET may be effective for inducing improvements in cardio metabolic health outcomes in healthy adults and those with an adverse cardio metabolic risk profile.
CRD42016037946.
This study aimed to compare the effects of three resistance training (RT) programs differing in the magnitude of velocity loss (VL) allowed in each exercise set: 10%, 30%, or 45% on changes in ...strength, vertical jump, sprint performance, and EMG variables. Thirty‐three young men were randomly assigned into three experimental groups (VL10%, VL30%, and VL45%; n = 11 each) that performed a velocity‐based RT program for 8 weeks using only the full squat exercise (SQ). Training load (55–70% 1RM), frequency (2 sessions/week), number of sets (3), and inter‐set recovery (4 min) were identical for all groups. Running sprint (20 m), countermovement jump (CMJ), 1RM, muscle endurance, and EMG during SQ were assessed pre‐ and post‐training. All groups showed significant (VL10%: 6.4–58.6%; VL30%: 4.5–66.2%; VL45%: 1.8–52.1%; p < 0.05–0.001) improvements in muscle strength and muscle endurance. However, a significant group × time interaction (p < 0.05) was observed in CMJ, with VL10% showing greater increments (11.9%) than VL30% and VL45%. In addition, VL10% resulted in greater percent change in sprint performance than the other two groups (VL10%: −2.4%; VL30%: −1.8%; and VL45%: −0.5%). No significant changes in EMG variables were observed for any group. RT with loads of 55–70% 1RM characterized by a low‐velocity loss (VL10%) provides a very effective and efficient training stimulus since it yields similar strength gains and greater improvements in sports‐related neuromuscular performance (jump and sprint) compared to training with higher velocity losses (VL30%, VL45%). These findings indicate that the magnitude of VL reached in each exercise set considerably influences the observed training adaptations.
Understanding strength changes with resistance training is important in human performance. It also enables better understanding into the expected magnitude of strength increase and factors that ...influence this change over time.
Squat, bench press, and deadlift scores were collated from 407 powerlifting meets (n = 1896 unique competitors: ~625 females, ~1270 males) between 2003 and 2018. Absolute (in kilograms) and relative starting strength (in kilograms per body weight) for each lift type was expressed for both sexes. Maximum and overall strength gain per day and per year (in kilograms) was calculated by comparing first and final, or maximum scores for each lift, respectively, and considered based on strength quartile classification. Paired and independent t-tests compared strength changes from baseline and between sexes. One-way ANOVAs compared strength changes between quartiles. Pearson correlations assessed relationships between strength changes over time, and baseline strength, number of competitions, and total days competing.
Maximum strength adaptations were greater for squat (20.2-25.4 kg·yr-1) and deadlift (18.1-21.1 kg·yr-1) compared with bench press (10.5-12.8 kg·yr-1, P ≤ 0.001). However, the change in absolute (all lifts: P = 0.247-0.379) and relative strength (all lifts: P = 0.641-0.821) did not differ between sexes. For females, maximum strength gain per day did not differ by quartile (all lifts: P = 0.091-0.746), nor did overall strength gain per day (P = 0.151-0.575). Conversely, males in the fourth quartile generally displayed lower maximum and overall strength gain per day.
These findings show differences in strength gain between upper- and lower-body lifts, but not sex differences in the change in strength. In line with previous research, the strongest males likely gain strength more slowly than weaker counterparts. Professionals should consider this information in the training, assessment, and long-term benchmarking of athletes whose sports require a focus on muscular strength.
Background:
Previous studies have shown that eccentric training has a positive effect on Achilles tendinopathy, but few randomized controlled trials have compared it with other loading-based ...treatment regimens.
Purpose:
To evaluate the effectiveness of eccentric training (ECC) and heavy slow resistance training (HSR) among patients with midportion Achilles tendinopathy.
Study Design:
Randomized controlled trial; Level of evidence, 1.
Methods:
A total of 58 patients with chronic (>3 months) midportion Achilles tendinopathy were randomized to ECC or HSR for 12 weeks. Function and symptoms (Victorian Institute of Sports Assessment–Achilles), tendon pain during activity (visual analog scale), tendon swelling, tendon neovascularization, and treatment satisfaction were assessed at 0 and 12 weeks and at the 52-week follow-up. Analyses were performed on an intention-to-treat basis.
Results:
Both groups showed significant (P < .0001) improvements in Victorian Institute of Sports Assessment–Achilles and visual analog scale from 0 to 12 weeks, and these improvements were maintained at the 52-week follow-up. Concomitant with the clinical improvement, there was a significant reduction in tendon thickness and neovascularization. None of these robust clinical and structural improvements differed between the ECC and HSR groups. However, patient satisfaction tended to be greater after 12 weeks with HSR (100%) than with ECC (80%; P = .052) but not after 52 weeks (HSR, 96%; ECC, 76%; P = .10), and the mean training session compliance rate was 78% in the ECC group and 92% in the HSR group, with a significant difference between groups (P < .005).
Conclusion:
The results of this study show that both traditional ECC and HSR yield positive, equally good, lasting clinical results in patients with Achilles tendinopathy and that the latter tends to be associated with greater patient satisfaction after 12 weeks but not after 52 weeks.
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