Association between Oxygen Consumption and Surface Electromyographic Amplitude and Its Variation within Individual Calf Muscles during Walking at Various Speeds

Sensitivity to change of quadriceps and hamstrings muscle wearable electromyography outcomes during a professional soccer match

Textile electromyography (EMG) was used to investigate neuromuscular activity during professional soccer matches, providing insights into performance optimization and injury prevention. This explorative study aimed to (1) describe the EMG activity of the quadriceps and hamstrings and (2) identify the metrics most sensitive to changes between the first and second half. Seven players (age: 23.1 ± 5.7 years; height: 1.82 ± 0.05 m; weight: 77.6 ± 10 kg) were evaluated. EMG outcomes included EMG amplitude, intensity distribution, and usual bout duration for dominant (D) and non-dominant (N.D) muscles. Hamstring activity averaged 47% (D) and 43% (N.D) of %EMGMVC, while quadriceps averaged 32% (D) and 27% (N.D). Most time was spent at the lowest EMG intensity and 13% at the highest intensity. Bout amplitudes (37-54%EMGMVC) and durations (14-17s) varied between muscle groups and limbs. The hamstrings' usual EMG bout amplitude (N.D) was the most sensitive, showing a 12% reduction (effect size [ES] = 0.64, p = 0,01). The most substantial percentage change was observed in the hamstrings' duration > 100% EMGMVC (D), which decreased by 27% (ES = 0.14, p = 0.57) with other metrics showing smaller reductions. This study highlights the potential of textile EMG to quantify neuromuscular demands during soccer matches, offering valuable tools for performance monitoring and tailored interventions to enhance training and prevent injuries.

Correlation of cervical-inspiratory-muscle electromyography and oxygen uptake during treadmill walking

For measurements of exercise intensity, an individual's oxygen uptake (V̇O2) is measured with an exhaled gas analyzer that involves a mask, but exercise coaching would benefit if an individual's V̇O2 could be estimated with more easily obtained predictors. We investigated the predictability of V̇O2 by electromyography (EMG) of the neck inspiratory muscles. We analyzed the EMG results of the sternocleidomastoid (EMGst) and scalene (EMGsc) muscles of 14 healthy adults who performed a treadmill exercise load test. Their V̇O2, inspiratory flow rate, and heart rate were simultaneously recorded during the exercise. The exercise load test was performed twice at a ≥2-day interval. The first visit was an incremental exercise test, and the second was a repeated two-load exercise test at levels below and above the participant's ventilatory threshold (VT) as determined in the first test. We observed that the integrated EMG values for each exercise load showed partially significant positive correlations with the EMGst and EMGsc. However, the cervical inspiratory muscle EMGs did not show as high a correlation as the minute ventilation. These results indicate that (i) EMG of the cervical inspiratory muscles could be used to estimate V̇O2, but (ii) these EMG parameters alone should be considered insufficient for estimating V̇O2.

An Investigation of Surface EMG Shorts-Derived Training Load during Treadmill Running

The purpose of this study was two-fold: (1) to determine the sensitivity of the sEMG shorts-derived training load (sEMG-TL) during different running speeds; and (2) to investigate the relationship between the oxygen consumption, heart rate (HR), rating of perceived exertion (RPE), accelerometry-based PlayerLoadTM (PL), and sEMG-TL during a running maximum oxygen uptake (V˙O2max) test. The study investigated ten healthy participants. On day one, participants performed a three-speed treadmill test at 8, 10, and 12 km·h-1 for 2 min at each speed. On day two, participants performed a V˙O2max test. Analysis of variance found significant differences in sEMG-TL at all three speeds (p < 0.05). A significantly weak positive relationship between sEMG-TL and %V˙O2max (r = 0.31, p < 0.05) was established, while significantly strong relationships for 8 out of 10 participants at the individual level (r = 0.72-0.97, p < 0.05) were found. Meanwhile, the accelerometry PL was not significantly related to %V˙O2max (p > 0.05) and only demonstrated significant correlations in 3 out of 10 participants at the individual level. Therefore, the sEMG shorts-derived training load was sensitive in detecting a work rate difference of at least 2 km·h-1. sEMG-TL may be an acceptable metric for the measurement of internal loads and could potentially be used as a surrogate for oxygen consumption.

Oxygen Consumption (VO2) and Surface Electromyography (sEMG) during Moderate-Strength Training Exercises

Oxygen consumption (VO₂) during strength training can be predicted through surface electromyography (sEMG) of local muscles. This research aimed to determine relations between VO₂ and sEMG of upper and lower body muscles to predict VO₂ from sEMG during moderate-intensity strength training exercises. Of the 12 participants recruited, 11 were divided into two groups: untrained (n = 5; with no training experience) and trained (n = 6; with 2 months of training experience). On different days, each individual completed six training sessions. Each participant performed training sessions consisting of three types of dumbbell exercises: shoulder press, deadlift, and squat, while wearing a mask for indirect calorimetric measurements of VO₂ using the Cortex Metalyzer 3B. sEMG measurements of the bilateral middle deltoid, lumbar erector spinae, quadriceps (rectus femoris), and hamstring (biceps femoris) muscles were recorded. The VO₂ was predicted from sEMG root mean square (RMS) values of the investigated muscles during the exercise period using generalized estimating equation (GEE) modeling. The predicted models for the three types of exercises for the untrained vs. trained groups were shoulder press [QIC = 102, * p = 0.000 vs. QIC = 82, * p = 0.000], deadlift [QIC = 172, * p = 0.000 vs. QIC = 320, * p = 0.026], and squat [QIC = 76, * p = 0.000 vs. QIC = 348, * p = 0.001], respectively. It was observed that untrained vs. trained groups predicted GEE models [quasi-likelihood under an independence model criterion (QIC) = 368, p = 0.330 vs. QIC = 837, p = 0.058], respectively. The study obtained significant VO₂ prediction models during shoulder press, deadlift, and squat exercises using the right and left middle deltoid, right and left lumbar erector spinae, left rectus femoris, and right and left biceps femoris sEMG RMS for the untrained and trained groups during moderate-intensity strength training exercises.