Validity of Wearable Electromyographical Compression Shorts to Predict Lactate Threshold During Incremental Exercise...

Snarr, RL, Tolusso, DV, Hallmark, AV, and Esco, MR. Validity of wearable electromyographical compression shorts to predict lactate threshold during incremental exercise in healthy subjects. J Strength Cond Res 35(3): 702-708, 2021-Determination of lactate threshold (LT) is an important variable in improving cardiovascular endurance and performance. Unfortunately, monitoring LT during exercise uses a costly, invasive blood analysis. Recently, electromyography (EMG) has been deemed a potential method of monitoring exercise intensity and may provide a noninvasive technique to monitor lactate during exercise. The purpose of this investigation was to determine if wearable surface EMG technology, acquired from specialized compression shorts, could estimate the LT work rate during incremental cycling. Thirteen men (n = 9) and women (n = 4) completed a maximal exercise test on a cycle ergometer. Blood lactate was measured every minute, whereas EMG was recorded throughout at the site of the vastus lateralis. Lactate and EMG thresholds were calculated using the Dmax method and compared using a Wilcoxon matched-pairs signed-rank test. Results demonstrated no significant differences between lactate and EMG thresholds in regards to work output (p = 0.83), percent maximal heart rate (p = 0.13; Cohen's d = 0.43), or percent peak oxygen consumption (p = 0.64; Cohen's d = 0.09). This confirms that both lactate and EMG exhibit similar properties (i.e., increasing exponential values) during incremental exercise. A possible mechanism includes the rise in blood lactate concentration, which increases motor unit recruitment in an attempt to maintain proper cadence and force output during incremental exercise. Thus, a coincidental, exponential increase in EMG amplitude may occur. Therefore, wearable EMG compression gear may provide a viable field tool for monitoring training intensity and predicting LT work rates.