(14) MAXIMAL EXERCISE AND POSTURAL STABILITY: A COMPARATIVE ANALYSIS OF FATIGUE ACROSS DIFFERENT MODES OF EXERCISE

Professional, recreational, and tactical athletes regularly perform maximal effort exercise (MEE). The fatiguing nature of MEE may negatively impact postural stability (PS), which is critical for performance. Decrements in PS may increase injury risk due to slips, trips, and falls. Interestingly, studies indicate that PS tends to decline following treadmill (TM) graded maximal exercise tests (GXT), whereas this decline is not as pronounced in cycle ergometer GXT. Given that athletes commonly engage in MEE involving both upper and lower extremities, a gap remains in understanding how PS is influenced by non-TM MEE and further research is needed to elucidate the differential effects of these exercise modes on PS.

Purpose: To assess the effects on PS of two distinct modes of inducing maximal fatigue via a GXT performed with a TM and an airbike (AB).

Methods: A total of 15 healthy adults (9M, 6F, age=29.1±8.0, hheight=1.74±0.06, mass=76.0±15.1) completed two fatiguing protocols in a randomized order 2 to 10 days apart. The TM GXT followed the WFI protocol of alternating increasing speed by .5 mph or incline by 2% every minute. The novel AB protocol utilized upper and lower extremities, and increased wattage by 20W (females) or 25W (males) each minute. PS was assessed via 15s of eyes closed quiet standing on dual force plates and was tested before and after the GXTs. A 2x2 Repeated measures factorial ANOVA with two levels of time (pre-, post) and fatigue method (TM, AB) was conducted. Cohen’s d effect sizes are reported. alpha = 0.05

Results: There was no difference for mean time to exercise failure (p=0.767), peak respiratory exchange rate (RER) (p=0.114), or RPE (p=0.499) between fatigue methods, suggesting participants were fatigued similarly. There was no significant impact of fatigue method or an interaction with time on any PS variable. There was a significant and large time effect on mean velocity (p=0.003, d=3.30), mean velocity AP (p=0.002, d=3.32), and total excursion (p=0.004, d=3.81), such that both GXTs impaired PS similarly (Figure 1).

Conclusion: No significant difference was found in PS between the two GXTs, suggesting that PS effects are not specific to fatigue method. Previous research suggests that PS decreases immediately following MEE but improves to above baseline values following 8-13 minutes of rest. Thus, a limitation was only assessing PS immediately following the MEE and not retesting PS after a recovery period.

PRACTICAL APPLICATIONS: Individuals should take caution when continuing to exercise following MEE due to decreased PS and increased injury risk. When possible, short breaks should be interspersed throughout maximal exercise. Strength and conditioning professionals should be cautious when programming to avoid placing movements requiring precise PS after MEE exercise. Future research should further explore how mode of exercise impacts PS metrics and duration of rest time needed to return to baseline PS.

Acknowledgements: None