• The internal and external demands of multi-directional running and the subsequent effect on side cut biomechanics in male and female team sport athletes

      Smith, Grace; Highton, Jamie; Twist, Craig; Oxendale, Chelsea L. (University of Chester, 2021-11)
      The aim of this thesis was to examine the physiological and biomechanical responses to multi-directional running in male and female team sport athletes. Chapter 4 compared measures of energy expenditure derived from indirect calorimetry and microtechnology, as well as high power and high-speed activity, during linear and multi-directional running. Measured energy expenditure was higher during the multidirectional trial (9.0 ± 2.0 cf. 5.9 ± 1.4 kcal.min-1), whereas estimated energy expenditure was higher during the linear trial (8.7 ± 2.1 cf. 6.5 ± 1.5 kcal.min-1). Whilst measures of energy expenditure were strongly related (r > 0.89, p < 0.001), metabolic power underestimated energy expenditure by 52% (95% LoA: 20-93%) and 34% (95% LoA: 12-59%) during the multi-directional and linear trial, respectively. Time at high power was 41% (95% LoA: 4-92%) greater than time at high speed during the multidirectional trial, whereas time at high power was 5% (95% LoA: -17-9%) lower than time at high speed during the linear trial. Chapter 5 explored the internal and external responses to linear and multi-directional running, specifically examining if measures of high speed and high power reflect changes in internal load. High speed distance (p < 0.001) was higher during the linear trial, whereas time at high power (p = 0.046) and accelerations performed (p < 0.001) were higher during the multi-directional trial. Summated HR (-0.8; ±0.5, p = 0.003), B[La] (-0.9; ±0.6, p = 0.002) and RPE (-0.7; ±0.6, p = 0.024) were higher during the multi-directional trial. There was a large difference in the ratio of high speed:summated HR (1.5; ±0.5, p = 0.001) and high speed:total V̇O2 (2.6; ±1.2, p < 0.001) between linear and multi-directional running, whilst high power:summated HR (0.3; ±0.5, p = 0.246) and high power:total V̇O2 (0.1;±0.8, p = 0.727) were similar. A small decrement in knee flexor torque was observed after the multi-directional (0.4; ±0.4, p = 0.017) and linear (0.2; ±0.3, p = 0.077) trials, respectively. Collectively, Chapters 4 and 5 reveal that more directional changes induce a greater internal response, despite reducing the high-speed distance someone is likely to cover. High power better reflects internal responses to multidirectional running than high speed, but microtechnology cannot be used to determine the absolute energy cost of multi-directional running. Chapters 6 and 7 explored alterations in side cut biomechanics in males and females immediately (Chapter 6) and 48 h (Chapter 7) after multi-directional running. In Chapter 6, 20 m sprint time was higher (ES: 0.65 – 1.17, p < 0.001) after multidirectional running, indicating the presence of fatigue. Males and females displayed trivial to moderate changes in trunk flexion (0.16 – 0.28, p = 0.082), peak hip internal rotation (0.46 – 0.54, p = 0.090), and knee flexion (0.17 – 0.41, p = 0.055) and higher knee abduction (0.40 – 0.51, p = 0.045) and internal rotation (0.59 – 0.81, p = 0.038) angular velocities, during the weight acceptance phase of side cuts after multidirectional running. Peak hip extensor (0.19 – 0.29, p = 0.055) and knee internal rotation moment (0.22 – 0.34, p = 0.052) displayed trivial to small increases after multidirectional running, whereas peak hip external rotation (0.44 – 0.57, p = 0.011), knee extensor (0.33 – 0.45, p = 0.003) moment and knee to hip extensor ratio (0.15 – 0.45, p = 0.005) were lower. In addition, IGRF displayed trivial to moderate changes (0.04 – 0.79, p = 0.066) and lateral GRF was lower (0.29 – 0.85, p = 0.002) after multidirectional running. In Chapter 7, CK concentration (2.4 – 4.94, p = 0.009), perceived muscle soreness (4.2 – 4.8, p < 0.001) and 20 m sprint time (0.6 – 0.9, p < 0.001) were higher 48 h after multi-directional running, indicating the presence of EIMD. Males and females displayed trivial to moderate changes in peak torso flexion (0.13 – 0.35, p = 0.055), hip internal rotation angular velocity (0.43 – 0.64, p = 0.073) and more knee internal rotation (0.31 – 0.5, p = 0.009) 48 h after multi-directional running. A tendency for an interaction between sex and time was noted for peak knee flexion (p = 0.068) and internal rotation angular velocity (p =0.057), with males only displaying a moderate increase. Males and females also displayed a lower peak knee extensor moment (0.43 – 0.56, p = 0.001) and a small increase in extensor moment (0.21 –0.46, p = 0.066) and knee external rotation moment (0.34 – 0.78, p = 0.062). An interaction between sex and time was noted for IGRF (p = 0.037); there was a large increase in IGRF at 48 h in females (1.4) but not males (0.08). For the first time, these data highlight multi-directional running which elicits fatigue and EIMD causes alterations in side cut biomechanics which can persist for at least 48 h. Specifically, both males and females performed side cuts in a more extended position, with higher peak angular velocities, and peak knee external rotation moments and less knee extensor moments both immediately and 48 h after multi-directional running.
    • Low body fat does not influence recovery after muscle-damaging lower-limb plyometrics in young male team sport athletes

      Fernandes, John; Lamb, Kevin; Twist, Craig; University of Chester
      Aim: This study assessed the influence of fat mass to fat-free mass ratio (FM:FFM) on recovery from plyometric exercise. Method: After assessment of body composition, 20 male team sport players (age 20.7 1.1 years; body mass 77.1 11.5 kg) were divided into low- (n = 10; 0.11 0.03) and normal- (n = 10; 0.27 0.09) fat groups based on FM:FFM ratio. Thereafter, participants completed measurements of knee extensor torque at 60 and 240 s􀀀1, countermovement jump flight time, plasma creatine kinase (CK) activity and perceived muscle soreness (VAS) before and at 0, 24 and 48 h after 10 10 maximal plyometric vertical jumps. Results: Evidence of muscle damage was confirmed by alterations in VAS, peak torque at 60 and 240 s􀀀1 and flight time at 0, 24 and 48 h after plyometric exercise (P < 0.05). CK was increased at 0 and 24 h (P < 0.05) but returned to baseline values by 48 h. No time by group e ects were observed for any of the dependent variables (P > 0.05). Conclusion: The current findings indicate that while muscle damage was present after plyometric exercise, the magnitude was similar across the two body composition groups. Applied practitioners can allow for a similar recovery time after plyometric exercise in those with low and normal body fat.