Objectives: The accepted wisdom within resistance training is that differing loads and corresponding repetition maximum (RM) ranges are optimal for inducing specific adaptations. For example, prominent organizations and their respective publications have typically prescribed heavy loads for maximal strength increases ( ≥ 85% 1RM/ ≤ 6RM), more moderate loads for hypertrophy (67-85% 1RM/6-12RM) and lighter loads for local muscular endurance (LME; ≤ 67% 1RM/ ≥ 12RM). Since we believe these recommendations originate from a misunderstanding and misinterpretation of DeLorme’s strength-endurance continuum, the aim of this narrative review is to discuss the preponderance of research surrounding training load and strength and LME adaptations. Design & Methods: Narrative Review Results: The current body of literature fails to support recommendations for the use of specific loads for specific strength, hypertrophy or LME adaptations. Furthermore, that the strength-endurance continuum originally presented by DeLorme was never intended to compare the use of heavier- and lighter-load resistance training, but rather to consider the adaptations to strength training and aerobically based endurance exercise. Finally, a lack of clarity considering absolute- and relative- LME has confounded understanding of this adaptation. Conclusions: The body of research supports that absolute LME appears to adapt as a result of maximal strength increases. However, relative LME shows minimal response to strength training with either heavier- or lighter-loads. We present the limitations of the current body of research and promote specifically detailed recent research as well as the importance of generality of strength and LME in both sporting and real-world settings.

Objectives: Researchers and practitioners in sports science aim to generate, and apply, knowledge to improve sports perfor mance. One area of interest is the role that muscular strength, and thus approaches to improve this (i.e. resistance training), has upon sports performance. In this review we briefly consider the evidence regarding an answer to the causal question “Does increasing an athletes’ strength improve sports performance?”. Design & Methods: We first consider the Applied Research Model for the Sport Sciences (ARMSS) to frame the problem and answer this. We then highlight barriers to answering it (and other causal questions) before offering suggestions to address these. Results: Muscular strength typically differentiates elite and non-elite athletes, and is correlated with proxy measures of sports performance. However, there is insufficient evidence to make a definitive statement regarding the causal effect of muscular strength upon sports performance. Conclusions: Considering the ARMSS, evidence is lacking whether improving muscular strength is causally related to sports performance. Present evidence is primarily observational and cross-sectional, experimental evidence is limited and focused upon proxy measures of sports performance, primarily conducted in small samples, and with little consideration regarding meaningfulness of effects. Suggestions to help improve research in this area and better answer this question include: larger sample sizes, determination of smallest effect sizes of interest for outcomes including muscular strength and proxy measures of sports performance (using both anchoring and/or expert opinion), and use of causal inference methods for observational data (actual sports performance, performance indicators, and fitness measures) including graphical causal diagrams and mediation analysis.

Objectives: To determine the relationships between the one-repetition maximum barbell hip thrust (1RM BHT) with change-of direction (COD) speed measured by the 505 in college-aged, recreationally-trained women. Design and Methods: Twenty college-aged women completed two testing sessions. In session 1, participants completed a 1RM BHT to measure absolute and relative lower-body strength, with an emphasis on the hip extensors. In Session 2, participants completed four trials (two per leg) of the 505 COD speed test. The mean of the two trials per leg was analyzed; the leg with the fastest 505 time was termed the dominant leg. Pearson’s correlations (p < 0.05) and regression scatter plots were used to calculate relationships between absolute and relative BHT strength and the 505 measured from the dominant and non-dominant leg. Results: There were significant relationships between relative strength measured by the 1RM BHT and the 505 from the domi nant (r = -0.473, p = 0.035) and non-dominant (r = -0.452, p = 0.046) legs, with ~21-22% explained variance. There were no significant relationships between absolute BHT strength and the 505 (r = -0.291 to -0.309, p = 0.184-0.213). Conclusions: Relative maximal hip extensor strength could be an important contributor to faster COD as measured by the 505 in college-aged, recreationally-trained females. The correlation strength and explained variance indicates that there are likely other factors beyond relative strength measured by the BHT that would contribute to a faster 505. Nonetheless, the results of this short communication provide support for developing hip extensor strength in females, as this could benefit COD speed in actions similar to those in the 505.

Objective: To determine the change in mechanical properties of sprinting performance across an 8-week off-season period in professional rugby league players. Design: Repeated measures Methods: Twenty-six professional rugby league players from a single rugby league team competing in Super League completed two assessments of linear sprint performance during final week of the season and second week of preseason. Linear split times were used to model the horizontal force-velocity profile and determine theoretical maximal force (F0), velocity (V0) and power (Pmax). Results: Our result indicated moderate-to-large increases in split times at each distance across the off-season period (ES = 0.86 to 1.24; most likely), indicative of a reduced sprinting ability. Furthermore, small reductions in F0 (ES -0.34 to -0.57; likely to very likely) were observed, whilst the reduction in V0 (ES = -0.81; most likely) and Pmax (ES = -0.62 to -1.03; most likely) were considered moderate in magnitude. Conclusions: An 8-week off-season period elicited negative changes in linear sprint times and the horizontal force-velocity profile of professional rugby league players. Such findings might have implications for preseason training loads and therefore, the off-season period requires careful consideration by practitioners and clinicians with regards to content and monitoring.

Objective: Intermittent Pneumatic Compression (IPC) use as a tool for recovery after exercise has recently become widespread among athletes. While there is anecdotal support for IPC, little research has been done to show its effectiveness in recovery. This study examined the impact of IPC use for recovery on performance, markers of inflammation, and a marker of muscle damage. Design: Eight university football athletes were recruited and subjected to IPC or passive recovery conditions in a randomized crossover manner following off-season training. Methods: Countermovement jump and 10 m sprint were evaluated before training, at 3 and 24 hours following training. Self reported soreness, blood markers of inflammation (interleukin-6, interleukin-10, and monocyte chemoattractant protein-1) and muscle damage (myoglobin) were measured before training, post-training, immediately after the recovery interventions, and at 3 and 24 hours post-training. Results: Significant time effects were observed in monocyte chemoattractant protein-1 and myoglobin suggesting an inflammatory response and muscle damage. No group differences were observed between recovery interventions for all measures. Conclusion: The results suggest that the IPC protocol used was not effective for the specific exercise paradigm and for the parameters measured in this population.