Is A 90 Min Recovery Period Following Fatiguing Handgrip Exercise Enough To Ensure Maximal Performance During A Critical Impulse Test (CIT) Or Incremental Exercise Test (IET)?

Introduction The critical impulse (CIT) and incremental exercise (IET) tests are used to quantify important performance capacity indices. The CIT requires maximal effort for 10 min enabling determination of the highest work rate sustainable by aerobic metabolism (CI) and anaerobic work capacity (W’). The IET involves 25 N increases every 3.5 min enabling determination of peak work rate (VO 2 ). Since these protocols are fatiguing, methodological considerations must be made when both parameters are assessed in a single session to ensure the second test performance is not compromised. Purpose To establish the reproducibility of the CIT and IET performance and to determine if 90 min of rest between trials allowed complete performance recovery. Methods 12 healthy recreationally active adults (24.3±3.9 yrs; 24.2±3.9 kg/m 2 ) completed rhythmic isometric forearm handgripping (1s contraction:2s relaxation) while supine with exercising muscles at heart level. Day 1 consisted of completing one exercise test followed 90 min later by the other. The order of test presentation was reversed on Day 2. Pre‐test maximal voluntary contractions (MVCs) were completed prior to each trial. CI was calculated as the average contraction impulse of the last 30s of the CIT and W’ was calculated as the area under the curve between CI and the maximal effort contractions over the course of the test. Peak IET Performance was calculated as the average impulse of final stage contractions. Total IET Work was calculated as the cumulative impulse from first to final contraction. Fatigue during the CIT and IET protocols were measured as the relative change in impulse from the pre‐test MVC to CI or Peak IET Performance respectively. Results Whether the CIT was preceded by the IET or not did not affect CIT performance: CI (p=0.2;ICC=0.9;CV=8.8) and W’ (p=0.5;ICC=0.9; CV=8.3%). Whether the IET was preceded by a CIT or not did not affect Peak IET Performance (p=0.6; ICC=1.0;CV=5.0) or Total IET Work (p=0.1;ICC=0.9;CV=11.5%). Total IET Work and W’ were equally reproducible (CV=8.0% vs. CV=7.0%; p=0.7). The impulse at the end of the CIT was ~86.6%±3.3% of the impulse at the end of the IET. Fatigue was greater during the CIT versus IET (−56.8% vs. −48.6%) (p<0.001). There was a strong correlation between CIT and Peak IET Performance (R 2 = 0.8; p<0.001) and W’ and Total IET Work (R 2 = 0.8; p<0.001). Conclusion Performance for both exercise tests demonstrates good day‐to‐day repeatability and 90 min of recovery is adequate to ensure peak performance in both tests. Therefore, to assess both CIT and Peak IET Performance in one session it is recommended at least 90 min of recovery be provided to ensure the prior fatiguing protocol does not compromise subsequent maximal performance. Support or Funding Information Alyssa M. Fenuta, MSc, is supported by Queen's University School of Graduate Studies Bruce Mitchell Academic Leadership Award.

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