COMPARING THE ACUTE EFFECTS OF WARM-UP STRATEGIES USING FREE-WEIGHT AND VARIABLE RESISTANCE ON STRENGTH AND POWER PERFORMANCE

Warm-up routines are typically designed to precondition the neuromuscular system for enhanced performance and reduced injury risk during subsequent high-intensity physical activities, including during strength training. As such, identifying an effective warm-up routine to augment muscular performance is of clear importance to strength (and other) coaches and athletes. Incorporating variable resistance (VR) via the use of chains or elastic bands during strength training alters the loading characteristics during exercises to impose a greater mechanical stimulus, however the impact of VR on subsequent free-weight exercise performance is unknown. Therefore, the aims of this thesis were to examine the acute effects of conditioning VR exercise compared to free-weight resistance (FWR) exercise on subsequent one-repetition maximum (1-RM) back squat and countermovement vertical jump (CMJ) height performance after the performance of a comprehensive, test-specific warm-up, and to examine possible alterations to mechanics and neuromuscular activity underpinning any changes. Techniques including 3D motion analysis, electromyography (EMG) and ground reaction force measurement were used in three studies on recreationally active volunteers experienced in squatting and jumping. In Study 1, significantly greater 1-RM squat-lift load (6.2 ± 5.0%; p 0.05) were detected in concentric phase EMG, knee angular velocity or peak knee flexion angle. Thus, performing a CLR warm-up enhanced subsequent free-weight 1-RM performance without kinematic changes; these data were considered to indicate a real 1-RM increase as the mechanics of the lift were not influenced. Study 2 followed an identical methodological design, however elastic bands were used to provide an inexpensive, portable, easily-implemented, and therefore more practical method of altering the load-time characteristics of the squat lift through VR. Significantly greater 1-RM squat load (7.7 ± 6.2%; p 0.05). However, statistical (p < 0.05) and practically-meaningful increases were detected in CMJ height (5.3-6.5%), net impulse (2.7-3.3%), take-off velocity (2.7-3.8%), peak power (4.4-5.9%), kinetic (7.1-7.2%) and potential (5.4-6.7%) energy, peak normalised rate of force development (12.9-19.1%), peak concentric knee angular velocities (3.1-4.1%) and mean concentric vastus lateralis (VL) EMG activity (27.5-33.4%) at all time points after the EB warm-up condition. Thus, when a complete CMJ-specific warm-up was provided, FWR squat had no additional effect on CMJ performance however the alteration of the squat lift force-time characteristics using EB led to a substantial CMJ enhancement. The findings from the present series of studies have important implications for research study design as the warm-up imposed and the resistive modality selected appear to influence subsequent movement performances, i.e. 1-RM back squat or CMJ performances. In previous studies, standardised (or no) warm-up protocols imposed before the baseline testing have been associated with subsequent enhancements in squat lift and CMJ performances following conditioning contractions, although it is unclear whether this is a consequence of acute neuromuscular alteration relating to the conditioning contractions or to the warm-up itself. Collectively, the present findings, show that physical performance can be enhanced in at least some conditions by application of conditioning contractions even after completion of a comprehensive, test-specific warm-up, which have important practical implications in the formulation of pre-performance warm-up routines where maximal force production is an important goal.N/

A Bibliometric Analysis of Soccer Biomechanics

Soccer biomechanics is a field that applies principles of mechanics to improve performance and reduce the risk of injury for soccer players. The purpose of this research is to perform a mapping review of the existing knowledge in the current literature, identify leading researchers and institutions, and explore emerging research topics. After conducting a mini literature review, a bibliometric analysis was carried out using the VOSviewer software. The data imported into VOSviewer was obtained from the Scopus database and included 951 records. The analysis performed included: (a) performance analysis to calculate the number of records per year and the authors with the most citations; (b) science mapping analysis (co-authorship, co-citation, and bibliographic coupling); and (c) clustering analysis through the co-occurrence analysis of author keywords. Our findings highlight a significant growth in research publications on soccer biomechanics over the past few decades, with a notable increase in the number of articles published in high-impact journals. Additionally, the clustering analysis resulted in seven clusters, with each cluster providing valuable insights into different aspects of soccer biomechanics, which clearly reflects the multifaceted nature of the field

The Influence of Unstable Load and Traditional Free-Weight Back Squat Exercise on Subsequent Countermovement Jump Performance

The purpose of the present study was to examine the effects of a back squat exercise with unstable load (UN) and traditional free-weight resistance (FWR) on subsequent countermovement jump (CMJ) performance. After familiarisation, thirteen physically active males with experience in resistance training visited the laboratory on two occasions during either experimental (UN) or control (FWR) conditions separated by at least 72 h. In both sessions, participants completed a task-specific warm-up routine followed by three maximum CMJs (pre-intervention; baseline) and a set of three repetitions of either UN or FWR back squat exercise at 85% 1-RM. During the UN condition, the unstable load was suspended from the bar with elastic bands and accounted for 15% of the total load. Post-intervention, three maximum CMJs were performed at 30 s, 4 min, 8 min and 12 min after the last repetition of the intervention. The highest CMJ for each participant was identified for each timepoint. No significant increases (p > 0.05) in jump height, peak concentric power, or peak rate of force development (RFD) were found after the FWR or UN conditions at any timepoint. The lack of improvements following both FWR and UN conditions may be a consequence of the low percentage of unstable load and the inclusion of a comprehensive task-specific warm-up. Further research is required to explore higher UN load percentages (>15%) and the chronic effects following the implementation of a resistance training programme

Feasibility, psychosocial effects, influence, and perception of elastic band resistance balance training in older adults

This study utilised feedback from older adults during balance-challenging, elastic band resistance exercises to design a physical activity (PA) intervention. Methods: Twenty-three active participants, aged 51 – 81 years, volunteered to perform a mini balance evaluation test and falls efficacy scale, and completed a daily living questionnaire. Following a 10 min warm-up, participants performed eight pre-selected exercises (1 × set, 8 – 12 repetitions) using elastic bands placed over the hip or chest regions in a randomised, counterbalanced order with 15 min seated rests between interventions. Heart rate (HR) and rate of perceived exertion (RPE) were measured throughout. Participant interview responses were used to qualify the experiences and opinions of the interventions including likes, dislikes, comfort, and exercise difficulty. Results: Similar significant (p \u3c 0.01) increases in HR (pre- = 83 – 85 bpm, mid- = 85 – 88 bpm, post-intervention = 88 – 89 bpm; 5 – 6 %) and RPE (pre- = 8 – 9, mid- = 10, post-intervention = 10 – 11) were detected during the PA interventions (hip and chest regions). Interview data revealed that participants thought the PA interventions challenged balance, that the exercises would be beneficial for balance, and that the exercises were suitable for themselves and others. Participants reported a positive experience when using the PA interventions with an elastic band placed at the hip or chest and would perform the exercises again, preferably in a group, and that individual preference and comfort would determine the placement of the elastic band at either the hip or chest. Conclusion: These positive outcomes confirm the feasibility of a resistance band balance program and will inform intervention design and delivery in future studies

Chain-loaded variable resistance warm-up improves free-weight maximal back squat performance

The acute influence of chain-loaded variable resistance exercise on subsequent free-weight one-repetition maximum (1-RM) back squat performance was examined in 16 recreationally active men. The participants performed either a free-weight resistance (FWR) or chain-loaded resistance (CLR) back squat warm-up at 85% 1-RM on two separate occasions. After a 5-min rest, the participants attempted a free-weight 1-RM back squat; if successful, subsequent 5% load additions were made until participants failed to complete the lift. During the 1-RM trials, 3D knee joint kinematics and knee extensor and flexor electromyograms (EMG) were recorded simultaneously. Significantly greater 1-RM (6.2 ± 5.0%; p .05) was found in concentric EMG, eccentric or concentric knee angular velocity, or peak knee flexion angle. Performing a CLR warm-up enhanced subsequent free-weight 1-RM performance without changes in knee flexion angle or eccentric and concentric knee angular velocities; thus a real 1-RM increase was achieved as the mechanics of the lift were not altered. These results are indicative of a potentiating effect of CLR in a warm-up, which may benefit athletes in tasks where high-level strength is required

Feasibility, Psychosocial Effects, Influence, and Perception of Elastic Band Resistance Balance Training in Older Adults

This study utilised feedback from older adults during balance-challenging, elastic band resistance exercises to design a physical activity (PA) intervention.MethodsTwenty-three active participants, aged 51-81 years, volunteered to perform a mini balance evaluation test and falls efficacy scale, and completed a daily living questionnaire. Following a 10 min warm-up, participants performed eight pre-selected exercises (1 × set, 8-12 repetitions) using elastic bands placed over the hip or chest regions in a randomised, counterbalanced order with 15 min seated rests between interventions. Heart rate (HR) and rate of perceived exertion (RPE) were measured throughout. Participant interview responses were used to qualify the experiences and opinions of the interventions including likes, dislikes, comfort, and exercise difficulty.ResultsSimilar significant (p < 0.01) increases in HR (pre- = 83-85 bpm, mid- = 85-88 bpm, post-intervention = 88-89 bpm; 5-6%) and RPE (pre- = 8-9, mid- = 10, post-intervention = 10-11) were detected during the PA interventions (hip and chest regions). Interview data revealed that participants thought the PA interventions challenged balance, that the exercises would be beneficial for balance, and that the exercises were suitable for themselves and others. Participants reported a positive experience when using the PA interventions with an elastic band placed at the hip or chest and would perform the exercises again, preferably in a group, and that individual preference and comfort would determine the placement of the elastic band at either the hip or chest.ConclusionThese positive outcomes confirm the feasibility of a resistance band balance program and will inform intervention design and delivery in future studies