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Physiological indicators are increasingly employed in sports training. However, studies on surface electromyography (sEMG) primarily focus on the analysis of isometric contraction. Research on sEMG related to isotonic contraction, which is more relevant to athletic performance, remains relatively limited. This paper examines the changes in the isotonic contraction performance of the male upper arm muscles resulting from long-term basketball training using the sEMG metrics. We recruited basketball physical education (B-PE) and non-PE majors to conduct a controlled isotonic contraction experiment to collect and analyze sEMG signals. The sample entropy event detection method was utilized to extract the epochs of active segments of data. Subsequently, statistical analysis methods were applied to extract the key sEMG time domain (TD) and frequency domain (FD) features of isotonic contraction that can differentiate between professional and amateur athletes. Machine learning methods were employed to perform ten-fold cross-validation and repeated experiments to verify the effectiveness of the features across the different groups. This paper investigates the key features and channels of interest for categorizing male participants from non-PE and B-PE backgrounds. The experimental results show that the F12B feature group consistently achieved an accuracy of between 80% and 90% with the SVM2 model, balancing both accuracy and efficiency, which can serve as evaluation indices for isotonic contraction performance of upper limb muscles during basketball training. This has practical significance for monitoring isotonic sEMG features in sports and training, as well as for providing individualized training regimens.
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http://dx.doi.org/10.3390/s25051355 | DOI Listing |
Free Radic Biol Med
August 2025
Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA. Electronic address:
Mechanisms of skeletal muscle fatigue are commonly studied under isometric conditions, which exclude muscle shortening and limit physiological relevance. We developed a novel in vitro protocol to examine isotonic fatigue using afterload contractions that permits the study of additional active (velocity, power, work) and passive (stiffness, energy loss) mechanical properties of muscle. During the development of this protocol, we examined the impact of shortening load during afterload contractions on the development of fatigue, and observed a relationship where fatigue onset is more rapid and severe with larger shortening loads (30 % vs.
View Article and Find Full Text PDFKnee
August 2025
School of Medicine, University of North Carolina Chapel Hill, Chapel Hill, NC, USA.
Background: Accessible measurements of multimodal strength are essential to clinical practice and outcome research. While isokinetic dynamometers are considered the gold standard for isometric and isokinetic strength measurement, their practical use is limited by the insufficiency to measure isotonic strength, high cost, and needs for extensive physical space. Establishing techniques to assess isotonic strength using a portable dynamometer may enhance performance evaluations.
View Article and Find Full Text PDFJ Neurophysiol
August 2025
Faculty of Sport, Technology and Health Sciences, St Mary's University, Twickenham, United Kingdom.
Muscle pain can alter corticospinal function, but the specific excitatory/inhibitory effects on the quadriceps across different levels of corticospinal neuron recruitment remain unclear. Furthermore, maximal force production is reduced with muscle pain, but how the rate of force development, a key component of neuromuscular function, remains less known. To investigate this, healthy participants completed an isometric maximal voluntary contraction (MVC) followed by submaximal, intermittent contractions after receiving a hypertonic saline injection into the vastus lateralis to cause quadriceps pain (HYP), or isotonic saline, a nonpainful control (ISO).
View Article and Find Full Text PDFAppl Physiol Nutr Metab
January 2025
Faculty of Kinesiology and Recreation Management, University of Manitoba, Winnipeg, MB, Canada.
As a novel, low-velocity resistance exercise method, eccentric quasi-isometric resistance exercise (EQI-RE) results in greater time under tension than traditional isotonic resistance exercise (TRD-RE) and is surmised to increase muscle mass and strength. However, females may be more fatigue-resistant than males when performing acute EQI-RE, which could lead to long-term differences in time under tension and resistance exercise volume. At present, studies have yet to compare muscle hypertrophy or strength improvements following TRD-RE and EQI-RE training, and whether sex differences exist in these outcomes.
View Article and Find Full Text PDFPLoS One
June 2025
Research Institute on Human and Societal Augmentation, National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, Chiba, Japan.
This study introduces an advanced computational model for simulating surface electromyography (sEMG) signals during muscle contractions. The model integrates five elements that simulate the chain of processes from motor intention to voltage variations over the skin. These elements include the motor control system, motor neurons, muscle fibers, biological tissues, and electrodes.
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