Kinetics and Kinematics of the Squat and Step-up in Well-Trained Rugby Players

Abstract

In order to examine the development of lower body strength using either bilateral or unilateral resistance training developmental rugby players (n = 33; mean training age = 5.4 ± 2.9 years; one repetition maximum (1RM) 90° squat = 178 ± 27 kg;) completed an 18-week randomised controlled training design (Bilateral group (BIL), n = 13; Unilateral group (UNI), n = 10; Comparison, n = 10). The 8-week training phase involved two lower body, volumeload matched resistance sessions per week (6-8 sets x 4-8 reps at 45-88% one repetition maximum [1RM]), differing only in the prescription of a bilateral (back squat) or unilateral (step-up) resistance exercise. Maximum strength was assessed by a randomised order of 1RM back squat and step-up testing and analysed for within-and between group differences using effect sizes (ES ± 90% confidence limits [CL]). Both training groups showed practically important improvements in their trained exercise (ES ± 90% CL: BIL = 0.67 ± 0.48; UNI = 0.74 ± 0.38) with transfer to their non-trained resistance exercise (BIL step-up = 0.27 ± 0.39: UNI squat = 0.42 ± 0.39). The difference between-groups in adaptation of squat strength was unclear (BIL ES =-0.34 ± 0.55), whilst the UNI group showed an advantage in step-up training (ES = 0.41 ± 0.36). The results demonstrate practically important increases in lower body strength can be achieved using bilateral or unilateral resistance training and development of that strength may be expressed in the movement not trained, supporting the transfer of strength training between exercises of similar joint movements and muscles. Coaches may choose to incorporate unilateral strength training where the prescription of bilateral training may be inhibited.

Reliability of kettlebell swing one and five repetition maximum

“…Due to the fact that commercially available kettlebell increments generally exceed the CV% and SWC demonstrated in this research ( i.e. , signal > noise) ( Appleby, Newton & Cormack, 2019 ), changes in performance based on an increase or decrease in 1RM or 5RM kettlebell swing performance can be considered practically meaningful. Future research could determine the effect of plate configuration upon biomechanical, physiological and perceptual characteristics of the swing as well as the resulting adaptations such training may reduce.…”

“…A useful aspect of determining test-retest reliability is that it allows calculation of the smallest worthwhile change (SWC) ( Appleby, Cormack & Newton, 2019 ; Appleby, Newton & Cormack, 2019 ). The SWC represents the smallest change in performance that is likely to be of practical importance for athletic performance ( Appleby, Cormack & Newton, 2019 ; Appleby, Newton & Cormack, 2019 ). There are numerous methods that have been proposed for calculating the SWC, including as a fraction (commonly 0.2) of the between participant SD ( Buchheit, 2016 ; Datson et al, 2021 ).…”

“…Using this method, the TE/CV% of the 1RM and 5RM kettlebell swing is less than the SWC. As a result, for a change in performance to be considered practically useful it must not only exceed the TE/CV% but in this case also exceed the SWC ( Appleby, Cormack & Newton, 2019 ; Appleby, Newton & Cormack, 2019 ). The findings of this work are similar to those of previous work examining a range of exercises such as the bench press, squat and arm curls where the TE/CV% was less than the SWC ( do Nascimento et al, 2017 ).…”

“…The ICC was classified by the following scale: ‘poor’ ICC = <0.5, ‘moderate’ ICC = 0.5–0.75, ‘good’ ICC = 0.75–0.9, and ‘excellent’ ICC = >0.9 ( Koo & Li, 2016 ). The smallest worthwhile change (SWC) was determined as 0.2 × between-participants SD ± 90% CL representing the smallest practically important change ( Appleby, Cormack & Newton, 2019 ; Appleby, Newton & Cormack, 2019 ; Tofari et al, 2015 ). If the CV% was smaller than the SWC, the 1RM and 5RM tests were considered sensitive enough to detect the SWC.…”

“…This concept is important in strength training environments as it provides quantification of the “noise” in a test ( Hopkins, 2000 ). Noise is the result of both biological and technical variation and can therefore be used to determine whether any change in performance can be considered practically important based on whether the inherent noise in the test has been exceeded ( Appleby, Newton & Cormack, 2019 ).…”