Surface electromyographic activity of the erector spinae and multifidus during arm- and leg-ergometer exercises in young healthy men

The effect of body position on cardiovascular, skeletal muscle and ventilatory responses to submaximal cycling

The completion of exercise in different body positions can impact the function of various components of the oxygen delivery pathway; however, the effect of the haemodynamic conditions induced by a semi-upright body position on the integrative physiological response to exercise is poorly understood. The purpose of this study was to explore the effect of a semi-upright body position on cardiac output (CO), vastus lateralis oxygen saturation (S m O 2 ${{S}_{{\mathrm{m}}{{{\mathrm{O}}}_2}}}$ ), oxygen consumption (V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_2}}}$ ) and ratings of perceived exertion (Borg RPE) during submaximal cycling. Twenty healthy individuals (22 ± 3 years, 50% female) each completed alternating 5-min bouts of submaximal upright and semi-upright (40° incline) cycling at 50 and 100 W. CO,S m O 2 ${{S}_{{\mathrm{m}}{{{\mathrm{O}}}_2}}}$ ,V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_2}}}$ and RPE were assessed at rest and at each exercise intensity during steady state. There was a main effect of intensity on the increase in CO,S m O 2 ${{S}_{{\mathrm{m}}{{{\mathrm{O}}}_2}}}$ ,V ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_2}}}$ and RPE (all P < 0.001). In a semi-upright position, the increase in CO (7.9 ± 2.8 vs. 6.4 ± 2.6 L/min, P < 0.001), RPE (median (interquartile range): 11 (9-13) vs. 10 (8-12), P = 0.013) and the decrease inS m O 2 ${{S}_{{\mathrm{m}}{{{\mathrm{O}}}_2}}}$ (-38 ± 23 vs. -21% ± 18%, P < 0.001) were greater than upright, while the increase inV ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_2}}}$ was attenuated (1.030 ± 0.130 vs. 1.154 ± 0.165 L/min, P < 0.001). These results suggest that while a semi-upright body position produces elevations in CO, these elevations do not seem to perfuse the active skeletal muscle. This may explain the elevation in RPE despite a blunting in the increase inV ̇ O 2 ${{\dot{V}}_{{{{\mathrm{O}}}_2}}}$ . Further work is required to understand the effects of a semi-upright exercise position on skeletal muscle activation and lower limb blood flow.

Myoelectric, Myo-Oxygenation, and Myotonometry Changes during Robot-Assisted Bilateral Arm Exercises with Varying Resistances

Robot-assisted bilateral arm training has demonstrated its effectiveness in improving motor function in individuals post-stroke, showing significant enhancements with increased repetitions. However, prolonged training sessions may lead to both mental and muscle fatigue. We conducted two types of robot-assisted bimanual wrist exercises on 16 healthy adults, separated by one week: long-duration, low-resistance workouts and short-duration, high-resistance exercises. Various measures, including surface electromyograms, near-infrared spectroscopy, heart rate, and the Borg Rating of Perceived Exertion scale, were employed to assess fatigue levels and the impacts of exercise intensity. High-resistance exercise resulted in a more pronounced decline in electromyogram median frequency and recruited a greater amount of hemoglobin, indicating increased muscle fatigue and a higher metabolic demand to cope with the intensified workload. Additionally, high-resistance exercise led to increased sympathetic activation and a greater sense of exertion. Conversely, engaging in low-resistance exercises proved beneficial for reducing post-exercise muscle stiffness and enhancing muscle elasticity. Choosing a low-resistance setting for robot-assisted wrist movements offers advantages by alleviating mental and physiological loads. The reduced training intensity can be further optimized by enabling extended exercise periods while maintaining an approximate dosage compared to high-resistance exercises.

A Comparative Electromyographic Analysis of Flying Squirrel and 3-Point Quadripod Exercise for Lumbar Multifidus Muscle Activations among Healthy Female Subjects

Physical therapists employ several exercises to alleviate low back pain (LBP). Electromyography (EMG) examination of exercises can monitor muscle activation to help clinicians determine the exercise’s effect on stabilisation, endurance, or strength. This study evaluated surface EMG activity comparison for Flying Squirrel Exercise (FSE) and the novel 3-Point Quadripod Exercise (3-PQE) to find the most effective exercise for stimulating the lumbar multifidus (LM) muscle. The study recruited 64 healthy young females (19–24 years). Raw data were normalized and are expressed as the percentage of maximum voluntary isometric contraction (%MVIC). The test–retest reliability of the EMG recordings was estimated using intraclass correlation coefficient (ICC3,1). One-way ANOVA was used to statistically analyse and compare the EMG amplitudes during the two exercises. The ICCs for 3-PQE and FSE were 0.94 (SEM, 21.7% MVIC) and 0.87 (SEM, 19.05% MVIC), respectively. The 3-PQE (69 ± 26% MVIC) demonstrated significantly higher activity than did FSE (30 ± 18% MVIC) (F = 15.573, p = 0.001). Thus, 3-PQE might be a feasible strategy for the prevention and rehabilitation of LBP in females.