Helme, M, Bishop, C, Emmonds, S, and Low, C. Validity and reliability of the rear foot elevated split squat 5 repetition maximum to determine unilateral leg strength symmetry. J Strength Cond Res 33(12): 3269–3275, 2019—The purpose of this study was to examine the validity and reliability of the rear foot elevated split squat (RFESS) 5 repetition maximum (5RM) test as a field method for measuring unilateral leg strength symmetry. As a validated method of testing symmetry, the RFESS 5RM may be used by strength and conditioning coaches and sports medicine staff to measure the presence of imbalances with minimal equipment and time. Twenty-six subjects (age = 23.8 ± 4.6 years, mass = 88.1 ± 10.7 kg, and height = 1.79 ± 0.1 m) with a minimum 2 years of strength and conditioning experience were recruited. After a familiarization session, subjects performed an incremental 5RM protocol on both legs, on 2 occasions where 3D motion and force data were collected. Moderate reliability of bar load symmetry was found between test and retest conditions correlation (intraclass coefficient = 0.73, 0.33–0.91) with no proportional bias between sessions. Validation of the exercise was analyzed using a correlation between asymmetries in mean set vertical ground reaction forces (vGRF) of the lead foot during the concentric phase, with bar load. When all maximal trials, from both test conditions, were analyzed, a most likely large positive correlation (0.57, 0.30–0.76) was found for mean set concentric lead foot vGRF. When a threshold level of load symmetry (96.54–103.46%) was applied, a most likely large positive correlation (r = 0.59, 0.14–0.84) between symmetry in lead foot vGRF was found in subjects who exceeded this limit. Conversely, analysis of subjects within the threshold produced unclear correlations. Findings of this study suggest the RFESS is a valid and reliable measure of unilateral leg strength symmetry. Practitioners are recommended to use this exercise to investigate the strength symmetry of athletes, but are guided to note that a threshold level of symmetry (96.54–103.46%) may be required to have been exceeded to indicate a true difference in vGRF production.

Helme, M, Emmonds, S, and Low, C. Is the rear foot elevated split squat unilateral? An investigation into the kinetic and kinematic demands. J Strength Cond Res 36(7): 1781–1787, 2022—The purpose of the study was to determine the unilateral nature of the rear foot elevated split squat (RFESS). Specifically, the production of force by the rear leg was examined to better understand its role, if any, toward successful completion of the exercise. Male volunteers were recruited ( n = 26, age = 23.8 ± 4.6 years, body mass = 88.1 ± 10.7 kg, and height = 1.79 ± 0.1 m), who were recreationally trained and engaged in a structured strength and conditioning program, including both bilateral and unilateral exercises, and had at least 2 years supervised training experience. Subjects participated in an incremental 5 repetition maximum protocol after familiarization. Kinetic data were recorded through 2 independent force plates, 1 integral to the floor and the second mounted on top of solid weightlifting blocks. Kinematic data were captured through 3-dimensional motion analysis. A total of 715 repetitions were analyzed, and the mean contribution of the lead foot to total vertical force production was 84.36 ± 3.6%. An almost certainly small positive correlation (rho = 0.25, confidence interval [CI] 0.18–0.33) was found between the percentage of force produced by the lead foot, with increasing exercise intensity. A most likely trivial, nonsignificant correlation (rho = −0.01, CI −0.09 to 0.06) with rear foot force production, representing the mass of the rear leg. Data from this study do not indicate that the rear foot contributes to the kinetic demands of the exercise and therefore suggests that the RFESS is a valid unilateral exercise.

The aim of this study was to analyse the relationship between unilateral leg strength, associated asymmetries and the injuries suffered by sub-elite Rugby League (RL) players in one competitive season. A prospective cohort design was used. Unilateral leg strength was measured using the rear foot elevated split squat five repetition maximum test. Injuries were recorded using the Orchard classification system and were used to quantify relative risk (RR), mean severity, burden, player availability and survival time. No measures of leg strength were related to RR, relative leg strength was found to have a significant, but not meaningful correlation with total time lost to lower body injury, lower body injury burden and lower body injury survival time. The data from the current study indicates a possible positive effect of increasing relative leg strength for injury outcomes in sub-elite RL players. This supports a heuristic that multi-joint lower body strength training for RL players has a potential dual effect of enhancing physical performance and reducing injury time loss, with minimal risk of harm.

Despite a robust body of evidence supporting both the need for and the effectiveness of physical fitness interventions in children aged 5–11, global fitness levels in this age group continue to decline. This systematic scoping review interrogates a critical, often overlooked dimension of this paradox: the pedagogy of fitness-intervention design and delivery. By analysing 106 primary research studies, the review exposes a consistent pattern. Interventions are predominantly highly structured (89%), rarely foster a mastery-oriented motivational climate (only 11%), and fail to report practitioner behaviours (65%). While most interventions yielded positive fitness outcomes, these gains were achieved without the use of pedagogical strategies known to support engagement, autonomy, and long-term adherence in children. This suggests that current approaches may achieve short-term physiological improvements but are limited in cultivating the motivational and developmental conditions necessary for sustained impact. The findings underscore a pressing need for future research to move beyond the “what” of fitness programming and rigorously address the “how.” Embedding and explicitly reporting pedagogical elements—such as supportive practitioner behaviours, autonomy-supportive structures, and mastery climates—could transform fitness interventions into developmentally appropriate, engaging, and sustainable experiences for children. Without this shift, we risk perpetuating interventions that are effective in the lab but ineffective in life.

Helme, M, Emmonds, S, Low, C, and Till, K. A novel case study approach to the investigation of leg strength asymmetry and Rugby League player's multidirectional speed. J Strength Cond Res 38(5): 941–947, 2024—Leg strength and multidirectional speed qualities have repeatedly been linked with increased performance during Rugby League (RL) match play and associated with career attainment. However, very little of this evidence for strength has been gained through unilateral measurements with no study available that has examined the impact of strength asymmetry, in this population, on speed qualities in RL players. Therefore, this study examined the association between unilateral strength, and as a novel development, the subject with the most extreme asymmetry was identified for further analysis. Fifty RL players undertook the rear foot elevated split squat 5 repetition maximum, 20-m linear sprint, and modified 505 change of direction test. The mean leg strength for the group was 88.92 ± 12.59 kg; when divided by body mass, the mean relative strength (REL) was 1.03 ± 0.17 kg·kg⁻¹, and the mean asymmetry was 3.21 ± 5.70%. The subject with the greatest asymmetry (subject A) had an imbalance of 33% and a mean leg strength of 75 kg (REL = 0.78 kg·kg⁻¹) and a body mass 1 SD above the group mean. Analysis of the group's data and that of subject A did not indicate that leg strength asymmetry was either frequent or harmful, with respect to speed performance. However, relative leg strength was associated with both improved linear and multidirectional speed. Practitioners are recommended to prioritize the development of relative leg strength and disregard the aspiration for between leg performance symmetry.