Non-local Muscle Fatigue Effects on Muscle Strength, Power, and Endurance in Healthy Individuals: A Systematic Review with Meta-analysis.

BACKGROUND: The fatigue of a muscle or muscle group can produce global responses to a variety of systems (i.e., cardiovascular, endocrine, and others). There are also reported strength and endurance impairments of non-exercised muscles following the fatigue of another muscle; however, the literature is inconsistent. OBJECTIVE: To examine whether non-local muscle fatigue (NLMF) occurs following the performance of a fatiguing bout of exercise of a different muscle(s). DESIGN: Systematic review and meta-analysis. SEARCH AND INCLUSION: A systematic literature search using a Boolean search strategy was conducted with PubMed, SPORTDiscus, Web of Science, and Google Scholar in April 2020, and was supplemented with additional 'snowballing' searches up to September 2020. To be included in our analysis, studies had to include at least one intentional performance measure (i.e., strength, endurance, or power), which if reduced could be considered evidence of muscle fatigue, and also had to include the implementation of a fatiguing protocol to a location (i.e., limb or limbs) that differed to those for which performance was measured. We excluded studies that measured only mechanistic variables such as electromyographic activity, or spinal/supraspinal excitability. After search and screening, 52 studies were eligible for inclusion including 57 groups of participants (median sample = 11) and a total of 303 participants. RESULTS: The main multilevel meta-analysis model including all effects sizes (278 across 50 clusters [median = 4, range = 1 to 18 effects per cluster) revealed a trivial point estimate with high precision for the interval estimate [- 0.02 (95% CIs = - 0.14 to 0.09)], yet with substantial heterogeneity (Q(277) = 642.3, p < 0.01), I2 = 67.4%). Subgroup and meta-regression analyses showed that NLMF effects were not moderated by study design (between vs. within-participant), homologous vs. heterologous effects, upper or lower body effects, participant training status, sex, age, the time of post-fatigue protocol measurement, or the severity of the fatigue protocol. However, there did appear to be an effect of type of outcome measure where both strength [0.11 (95% CIs = 0.01-0.21)] and power outcomes had trivial effects [- 0.01 (95% CIs = - 0.24 to 0.22)], whereas endurance outcomes showed moderate albeit imprecise effects [- 0.54 (95% CIs = - 0.95 to - 0.14)]. CONCLUSIONS: Overall, the findings do not support the existence of a general NLMF effect; however, when examining specific types of performance outcomes, there may be an effect specifically upon endurance-based outcomes (i.e., time to task failure). However, there are relatively fewer studies that have examined endurance effects or mechanisms explaining this possible effect, in addition to fewer studies including women or younger and older participants, and considering causal effects of prior training history through the use of longitudinal intervention study designs. Thus, it seems pertinent that future research on NLMF effects should be redirected towards these still relatively unexplored areas.

Foam Rolling Prescription: A Clinical Commentary.

Behm, DG, Alizadeh, S, Hadjizadeh Anvar, S, Mahmoud, MMI, Ramsay, E, Hanlon, C, and Cheatham, S. Foam rolling prescription: a clinical commentary. J Strength Cond Res 34(11): 3301-3308, 2020-Although the foam rolling and roller massage literature generally reports acute increases in range of motion (ROM) with either trivial or small performance improvements, there is little information regarding appropriate rolling prescription. The objective of this literature review was to appraise the evidence and provide the best prescriptive recommendations for rolling to improve ROM and performance. The recommendations represent studies with the greatest magnitude effect size increases in ROM and performance. A systematic search of the rolling-related literature found in PubMed, ScienceDirect, Web of Science, and Google Scholar was conducted using related terms such as foam rolling, roller massage, ROM, flexibility, performance, and others. From the measures within articles that monitored ROM (25), strength (41), jump (41), fatigue (67), and sprint (62) variables; regression correlations and predictive quadratic equations were formulated for number of rolling sets, repetition frequency, set duration, and rolling intensity. The analysis revealed the following conclusions. To achieve the greatest ROM, the regression equations predicted rolling prescriptions involving 1-3 sets of 2-4-second repetition duration (time for a single roll in one direction over the length of a body part) with a total rolling duration of 30-120-second per set. Based on the fewer performance measures, there were generally trivial to small magnitude decreases in strength and jump measures. In addition, there was insufficient evidence to generalize on the effects of rolling on fatigue and sprint measures. In summary, relatively small volumes of rolling can improve ROM with generally trivial to small effects on strength and jump performance.