The effects of strength training upon front foot contact ground reaction forces and ball release speed among high-level cricket pace bowlers.

The effects of an eight-week off-season strength training program upon lower-body strength, power, eccentric capacity, front foot contact (FFC) kinetics, and ball release speed (BRS) in pace bowlers were investigated. Ten elite-academy pace bowlers completed the intervention, and pre- and post-testing. Pre- and post-testing included: double (DLDL) and single leg (SLDL) drop landings; isometric mid-thigh pull (IMTP); countermovement jump; and pace bowling performance (two-over bowling spell measuring BRS and FFC kinetics). Changes from pre- to post-testing were assessed with paired sample t tests (p≤ 0.01), effects sizes and statistical parametrical mapping. Post-testing revealed a significant decrease in peak normalised vertical force during DLDL and SLDL with large effects and a significant, moderate effect increase in IMTP. There was no significant changes in BRS. Concomitantly, neither discrete scalar (p= 0.15-0.58) nor vector field analysis kinetics during FFC indicated significant changes. No significant alterations in FFC kinetics may explain the lack of improvement in BRS (pre = 31.55 ± 1.44 m/s; post = 31.79 ± 1.33 m/s). This study indicated an eight-week strength training program can improve strength and eccentric capacity in pace bowlers, and these changes when developed in the absence of skills training neither improved nor decreased pace bowling performance.

Does Delivery Length Impact Measures of Whole-Body Biomechanical Load During Pace Bowling?

PURPOSE: To investigate whether changes in delivery length (ie, short, good, and full) lead to alterations in whole-body biomechanical loading as determined by ground reaction force during front-foot contact of the delivery stride for pace bowlers. Current load-monitoring practices of pace bowling in cricket assume equivocal biomechanical loading as only the total number of deliveries are monitored irrespective of delivery length. METHODS: A total of 16 male pace bowlers completed a 2-over spell at maximum intensity while targeting different delivery lengths (short, 7-10 m; good, 4-7 m; and full, 0-4 m from the batter's stumps). In-ground force plates were used to determine discrete (vertical and braking force, impulse, and loading rates) and continuous front-foot contact ground reaction force. Repeated-measures analysis of variance (P < .05), effects size, and statistical parametrical mapping were used to determine differences between delivery lengths. RESULTS: There were no significant differences between short, good, and full delivery lengths for the discrete and continuous kinetic variables investigated (P = .19-1.00), with trivial to small effect sizes. CONCLUSION: There were minimal differences in front-foot contact biomechanics for deliveries of different lengths (ie, short, good, and full). These data reinforce current pace bowling load-monitoring practices (ie, counting the number of deliveries), as changes in delivery length do not affect the whole-body biomechanical loading experienced by pace bowlers. This is of practical importance as it retains simplicity in load-monitoring practice that is used widely across different competition levels and ages.

The relationship between inertial measurement unit-derived 'force signatures' and ground reaction forces during cricket pace bowling.

This study assessed the reliability and validity of segment measured accelerations in comparison to front foot contact (FFC) ground reaction force (GRF) during the delivery stride for cricket pace bowlers. Eleven recreational bowlers completed a 30-delivery bowling spell. Trunk- and tibia-mounted inertial measurement units (IMUs) were used to measure accelerations, converted to force, for comparisons to force plate GRF discrete measures. These measures included peak force, impulse and the continuous force-time curve in the vertical and braking (horizontal) planes. Reliability and validity was determined by intra-class correlation coefficients (ICC), coefficient of variation (CV), Bland-Altman plots, paired sample t-tests, Pearson's correlation and one-dimensional (1D) statistical parametrical mapping (SPM). All ICC (0.90-0.98) and CV (4.23-7.41%) were acceptable, except for tibia-mounted IMU braking peak force (CV = 12.44%) and impulse (CV = 18.17%) and trunk vertical impulse (CV = 17.93%). Bland-Altman plots revealed wide limits of agreement between discrete IMU force signatures and force plate GRF. The 1D SPM outlined numerous significant (p < 0.01) differences between trunk- and tibia-located IMU-derived measures and force plate GRF traces in vertical and braking (horizontal) planes. The trunk- and tibia-mounted IMUs appeared to not represent the GRF experienced during pace bowling FFC when compared to a gold-standard force plate.

The Effects of an Eight over Cricket Bowling Spell upon Pace Bowling Biomechanics and Performance within Different Delivery Lengths.

Pace bowlers must often perform extended bowling spells with maximal ball release speed (BRS) while targeting different delivery lengths when playing a multi-day match. This study investigated the effect of an eight over spell upon pace bowling biomechanics and performance at different delivery lengths. Nine male bowlers (age = 18.8 ± 1.7 years) completed an eight over spell, while targeting different lengths (short: 7-10 m, good: 4-7 m, full: 0-4 m from the batter's stumps, respectively) in a randomized order. Trunk, knee and shoulder kinematics and ground reaction forces at front foot contact (FFC), as well as run-up velocity and BRS were measured. Paired sample t-tests (p ≤ 0.01), Hedges' g effect sizes, and statistical parametrical mapping were used to assess differences between mean variables from the first and last three overs. No significant differences (p = 0.05-0.98) were found in any discrete or continuous variables, with the magnitude of difference being trivial-to-medium (g = 0.00-0.73) across all variables. Results suggest pace bowlers sustain BRS through a single eight over spell while tolerating the repeatedly high whole-body biomechanical loads as suggested by maintaining the kinematics or technique at the assessed joints during FFC. Practically, the findings are advantageous for bowling performance and support current bowling load monitoring practices.