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Beattie, K and Ruddock, AD. The role of strength on punch impact force in boxing. J Strength Cond Res 36(10): 2957-2969, 2022-The ability to punch with a high impact force is beneficial to boxers as there is an increased likelihood of success. Punch impact force differentiates between performance level, weight class, gender, and punch type in competitive boxers. Although technique is likely to play a major role in punch impact force, the capabilities of the neuromuscular system may also be a limiting factor. This review examines the role of strength on punch impact force in amateur and professional boxers. The maximal strength qualities of the lower body, as well as explosive strength qualities of both the upper and lower body, are largely associated with punch impact force in elite amateur boxers. Specifically, elite amateur boxers who punch with "high" impact forces have greater levels of lower-body maximal strength and explosive strength when compared with elite amateurs who punch with "low" impact forces. However, the maximal strength capabilities of the upper body are not associated with punch impact force and does not differentiate between elite boxers who punch with "high" and "low" impact forces. Therefore, based off the present evidence, this review recommends that for boxers who aim to develop their punch impact force, it may be advantageous to emphasize both maximal and explosive strength development of the legs, with only an explosive strength focus in the upper body. However, it is important to highlight that, to date, there are a lack of experimental studies in both elite amateur and professional boxing. Furthermore, there is a dearth of research in female boxing. Future experimental studies are needed to infer causality regarding the role that strength training has on punch impact force in both elite amateur and professional boxers.

World-class 100m sprinters need a combination of exceptional acceleration, maximum-velocity and speed endurance; each of which are dictated by their own complex interplay of physiological and biomechanical factors [1]. Previous research has highlighted the importance of lower-limb force production, and the direction of application, for elite sprint performance [2,3]. The countermovement jump (CMJ) is a popular explosive-strength assessment often utilised by coaches and sport scientists to ascertain an athlete’s ability to rapidly apply vertical force with their lower limbs [4]. Compared to other strength diagnostic tests, the CMJ is highly practical due to its simplicity, low physiological strain, cost and time-effective technology (i.e. smartphone app, contact mat, portable force platform). The CMJ can be used to monitor explosive-strength adaptation, direct gym programming and infer neuromuscular readiness of an athlete. In sprinters, previous research has found strong relationships between specific CMJ variables (i.e. jump height, peak power) and both acceleration (r = 0.52–0.86) [5-9] and maximum-velocity performance (r = 0.55-0.77) [10,11]. Consequently, depending on other confounding factors (i.e. sprint technique, anthropometrics, level of performance), it may be suggested that 30–75% of sprint performance variance is explained by explosive-strength [5-11]. However, previous research has mainly focused on sub-elite populations (100m personal best [PB] > 10.28s) [5,6,12,13] and there is a lack of literature investigating the CMJ characteristics of world-class elite male sprinters s (100m PB < 10.15s). yes

peer-reviewed Introduction Strength training can improve neuromuscular function in athletes (Zatsiorky, 1995). Previous literature has demonstrated that strength training can improve key performance indicators (i.e. economy, velocity at VO2 max, & anaerobic power/capacity) in competitive distance runners (Beattie et al., 2014). However, the practice of strength training in distance runners is still a novel training modality. Traditionally, for unknown reasons, distance runners have been cautious to strength train. One potential reason is that athletes and coaches are unaware of the neural adaptations of strength training (musculotendinous stiffness, motor unit recruitment and synchronisation, rate coding, intra- and inter-muscular coordination, and neural inhibition), and deliberate that strength training results solely in increased muscle mass, negatively effecting relative aerobic power and performance. The purpose of this study was to examine the effect of a 40 week strength intervention on body composition variables (mass, % body fat, overall-lean & leg-lean muscle) in competitive distance runners. Methodology Twenty competitive club-standard distance runners (n = 20; 28.2 ± 8.6 years; 71.6 ± 6.6 kg; 180.1 ± 6.8 cm) participated in the 40 week study. Participants were divided into two groups based on their personal preference. The two groups consisted of a ‘strength’ intervention group (ST; n = 11; 29.5 ± 10.0 years; 72.8 ± 6.6 kg; 182.8 ± 8 cm), and a control group (CON; n = 9; 27.4 ± 7.2 years; 70.2 ± 6.4 kg ; 177.4 ± 3.7 cm). Both the intervention and control groups were informed to train as normal throughout the 40 week study. The intervention group strength trained twice a week during the twenty week pre-season period, and once a week during the twenty week in-season ‘racing’ period. All strength sessions were coached by the author who is an experienced Strength & Conditioning coach. Each runner was assessed for maximal-strength (1 RM back squat), reactive-strength (drop-jump 30 cm) and body composition (dual energy X-ray absorptiometry) at week 0, week 20 and week 40. Results There was a significant ‘time x group’ interaction for maximal-strength and reactive-strength measures (p < 0.05) between both groups during the 40 weeks. However, there was not a significant difference for body composition variables (body mass, % body fat, overall-lean & leg-lean muscle) between both groups. Conclusion The results from this study show that 40 weeks of strength training can significantly improve maximal- and reactive-strength qualities, without significant changes to body composition (specifically overall-lean and leg-lean muscle). Interestingly, even though there were significant improvements in maximal- and reactive-strength qualities in the strength group, leg-lean muscle decreased over the 40 weeks. It is suggested that the strength improvements in the intervention group resulted from improved neural function of the leg musculature. This study demonstrates that runners can strength train to improve maximal and reactive force capabilities, and potentially distance running performance, without adding ‘unwanted’ lean muscle tissue.

peer-reviewed Introduction Economy is now thought to be one of the main performance indicators in elite distance runners. Economy is the amount of metabolic energy expended at a given velocity. In addition to cardiovascular capacity, economy is believed to be partly dictated by the neuromuscular system (Paavolainen et al 1999). Reactive-strength is the ability of the runner to have proficient eccentric and concentric muscular capabilities to rapidly absorb and utilise the elastic energy produced during each ground contact. This short ground contact phase in running is the only phase in which a runner can produce force to horizontally propel the body. The purpose of this study was to examine the relationship between economy, velocity at maximum oxygen uptake (V 2 max) and reactive-strength in competitive distance runners. Methodology Twenty competitive club runners (age 31.7 ± 8.4 years, height 162 ± 55.2 cm, weight 71.3 ± 6.9 kg and 2 max 58.8 ± 2.3 mL/kg/min) were recruited from local running clubs. Each runner was assessed for economy, V 2 max, and reactive-strength. The reactive-strength test assessed countermovement jump (CMJ) height (slow stretch shortening cycle performance) and drop-jump (DJ) reactive strength index (RSI) from a 30 cm box (fast stretch shortening cycle performance). Results There was no relationship found between economy (taken from the runner’s most economical velocity during the sub-maximal test) and reactive-strength performance (both CMJ height and DJ RSI) in competitive distance runners. However, the results showed that there was a moderate correlation between CMJ height (slow stretch shortening cycle function) and velocity at maximum oxygen uptake (V 2 max) (r = .52, p < .01). Conclusion The results from this study show that there is no relationship between economy and reactive-strength in competitive distance runners. However, it is possible that the economy protocol used was not specific to the current sample of runners. The sample consisted of middle- and long-distance runners. The most valid measurement of economy may be at specific race velocities (Berg, 2003). Future research in the area should assess economy by measuring steady-state oxygen consumption at specific race velocities to the runner.