Recovery of Force–Time Characteristics After Australian Rules Football Matches: Examining the Utility of the Isometric Midthigh Pull

Abstract

Purpose: This study assessed the utility of force–time characteristics from the isometric midthigh pull (IMTP) as a measure of neuromuscular function after elite-level Australian rules football matches. It was hypothesized that rate characteristics of force development would demonstrate a different response magnitude and recovery time course than peak force measurements. Methods: Force–time characteristics of the IMTP (peak force, 0- to 50-ms rate of force development [RFD], 100- to 200-ms RFD) were collected at 48 (G+2), 72 (G+3), and 96 h (G+4) after 3 competitive Australian rules football matches. Results: Meaningful reductions (>75% of the smallest worthwhile change) were observed at G+2, G+3, and G+4 for RFD 0–50 milliseconds (−25.8%, −17.5%, and −16.9%) and at G+2 and G+3 for RFD 100–200 milliseconds (−15.7% and −11.7%). No meaningful reductions were observed for peak force at any time point (G+2 −4.0%, G+3 −3.9%, G+4 −2.7%). Higher week-to-week variation was observed for RFD 0–50 milliseconds (G+2 17.1%, G+3 27.2%, G+4 19.3%) vs both RFD 100–200 milliseconds (G+2 11.3%, G+3 11.5%, G+4 7.2%) and peak force (G+2 4.8%, G+3 4.4%, G+4 8.4%). Conclusions: These findings highlight the potential use of rate characteristics from the IMTP as measures of neuromuscular function in elite sport settings, and in particular RFD 100–200 milliseconds due to its higher reliability. Interestingly, peak force collected from the IMTP was not meaningfully suppressed at any time point after elite Australian rules football match play. This suggests that rate characteristics from IMTP may provide more sensitive and valuable insight regarding neuromuscular function recovery kinetics than peak measures.

Identifying Reliable and Relatable Force–Time Metrics in Athletes—Considerations for the Isometric Mid-Thigh Pull and Countermovement Jump

“…The RPD during the CMJs concentric phase was considered reliable in the current study and is in agreement with the limited prior findings (ICC = 0.89-0.99; CV = 4.6-9.9%) [19,32,33,47]. Although RFD is often regarded as a key performance indicator for athletic performances [25][26][27], multiple studies have now called into question its inherent reliability. This makes RFD less than adequate for monitoring neuromuscular readiness and fatigue, as large changes will be necessary to overcome the standard error in the measurement (i.e., the changes observed in RFD may or may not be indicative of changes in neuromuscular status).…”

“…The volume of metrics provided by such companies is also concerning, as some variables may be more reliable during testing and, thus, more sensitive to change in the neuromuscular status of an individual [23,24]. For example, RFD is a popular variable derived from force plate testing that previous studies have identified as an acceptable strategy for monitoring athlete performance [25,26], as well as neuromuscular fatigue [26,27]. However, other studies demonstrated that RFD was unreliable and, thus, should be used in athlete monitoring with excess caution [6,8,11].…”

The Reliability of Neuromuscular and Perceptual Measures Used to Profile Recovery, and the Time-Course of Such Responses Following Academy Rugby League Match-Play

“…Prolonged perturbations (based on ES values) seen in some (i.e., F250), but not other (i.e., PF) variables suggest that maximal force production may be less sensitive to the influence of match-play when compared to those measures that include a velocity-component. This finding supports observations following Australian Rules Football match-play, in which the rate of force development was found to be more sensitive to the recovery of neuromuscular function than PF [44]. When performing sporting actions such as sprinting, jumping and changing direction, ground contact occurs in time intervals between 50-250 ms, therefore it may be more important to apply force quickly as opposed to producing maximal force [45].…”

“…Whilst responses to rugby match-play have been profiled using different measures, such as a CMJ [4,7,11], a plyometric push-up [14], and an adductor squeeze test [16], the present study is amongst the first to profile the effects of match-play on IMTP responses [44]. Although match-play did not influence PF during the IMTP, a large ES (0.95) was reported at +24 h following match-play compared to baseline measures, whilst small and trivial ES were observed thereafter.…”

Phase-Specific Changes in Rate of Force Development and Muscle Morphology Throughout a Block Periodized Training Cycle in Weightlifters

“…Strong correlations (r ≥ 0.70) have been observed between these variables and weightlifting performance [12,13,14]. However, research suggests that RFD is more closely related to most athletic tasks [15,16] and is more sensitive to fatigue [12,17]. Haff et al [18] reported that calculating RFD using specific time bands results in higher reliability than quantifying peak RFD values.…”