Presenters

Ben DaltonFollow

Faculty Sponsor Name

Dr. Garrett Hester

Additional Faculty

Trisha VanDusseldorp, Exercise Science & Sports Management, tvanduss@kennesaw.edu Yuri Feito, Exercise Science & Sports Management, yfeito@kennesaw.edu

Abstract (300 words maximum)

Previous research on fatigue using isometric contractions suggests that females are more fatigue resistant than males, but less is clear regarding fatigue induced by dynamic contractions. PURPOSE: To determine sex differences for explosive voluntary neuromuscular characteristics of the plantar flexors (PFs) during a dynamic fatiguing task. METHODS: Recreationally active males (n=14; 22.4±2.2 yrs) and females (n=15; 20.9±2.5 yrs) performed a fatiguing task of the PFs consisting of 60 maximal isotonic contractions at 30% of their maximal isometric strength using a dynamometer. Peak power (PP), optimal velocity (OV), and optimal torque (OT) were calculated from the first five contractions of the fatigue task and five maximal isotonic contractions performed after the fatigue task. Power was calculated as the product of angular velocity and torque and PP was recorded. In addition, velocity and torque at the moment in time PP occurred were recorded as OV and OT, respectively. Rate of electromyography rise for the medial gastrocnemius (RERMG) and soleus (RERSOL) was calculated as the linear slope of the normalized electromyography-time curve. Two-way (time ´ group) repeated measures ANOVAs were used to determine sex differences across time. RESULTS: Regardless of sex, PP (-16%; pppSOL remained unchanged for both sexes (-6%; p>0.05), while RERMG was only reduced in males (-21%;p=0.001). CONCLUSION: Our data indicate that explosive contractile characteristics are diminished similarly in males and females during a dynamic fatiguing task, but it appears the muscle-specific physiological mechanisms may differ between sexes.

Project Type

Poster

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FATIGUE-INDUCED SEX DIFFERENCES FOR EXPLOSIVE NEUROMUSCULAR CHARACTERISTICS OF THE PLANTAR FLEXORS

Previous research on fatigue using isometric contractions suggests that females are more fatigue resistant than males, but less is clear regarding fatigue induced by dynamic contractions. PURPOSE: To determine sex differences for explosive voluntary neuromuscular characteristics of the plantar flexors (PFs) during a dynamic fatiguing task. METHODS: Recreationally active males (n=14; 22.4±2.2 yrs) and females (n=15; 20.9±2.5 yrs) performed a fatiguing task of the PFs consisting of 60 maximal isotonic contractions at 30% of their maximal isometric strength using a dynamometer. Peak power (PP), optimal velocity (OV), and optimal torque (OT) were calculated from the first five contractions of the fatigue task and five maximal isotonic contractions performed after the fatigue task. Power was calculated as the product of angular velocity and torque and PP was recorded. In addition, velocity and torque at the moment in time PP occurred were recorded as OV and OT, respectively. Rate of electromyography rise for the medial gastrocnemius (RERMG) and soleus (RERSOL) was calculated as the linear slope of the normalized electromyography-time curve. Two-way (time ´ group) repeated measures ANOVAs were used to determine sex differences across time. RESULTS: Regardless of sex, PP (-16%; pppSOL remained unchanged for both sexes (-6%; p>0.05), while RERMG was only reduced in males (-21%;p=0.001). CONCLUSION: Our data indicate that explosive contractile characteristics are diminished similarly in males and females during a dynamic fatiguing task, but it appears the muscle-specific physiological mechanisms may differ between sexes.