Diurnal Sensitivity Of Muscle Force And Acceleration Parameters Of The Upper Limb

Document Type

Conference Presentation

Department

Health, Exercise, and Sport Sciences Department

Conference Title

American College of Sports Medicine - Medicine & Science in Sports & Exercise conference

Organization

American College of Sports Medicine

Location

San Francisco, CA

Date of Presentation

1-1-2020

Journal Publication

Medicine & Science in Sports & Exercise

ISSN

0195-9131

Volume

52

First Page

210

Abstract

Novel technology permits more precise investigation of motor function. Limited data exist on diurnal variation in force and acceleration parameters of the upper limb. PURPOSE: To detect the optimal time of day for maximum power output and development rate in unilateral row and press motions. METHODS: We tested 112 physically active male and female subjects on Proteus (Proteus Motion, USA). In total, they performed 2,750 unilateral, isotonic sets, evenly divided between rows and presses. Loads were applied through three-dimensional magnetic resistance at 10lb (862 sets), 15lb (646 sets), 20lb (612 sets), and 25lb (630 sets). Testing was performed at various times over a 14-hour span (6:00am to 8:00pm). For each individual set, Proteus calculated average peak power of all repetitions (PPmean), highest power achieved during any single repeition (PPmax), average peak force development rate across all repetitions (PFDRmean), and the highest rate achieved during a single repetition (PFDRmax). Mixed model ANOVA with repeated measures tested the differences in these parameters between push and pull motions, loads applied, and times of day. Linear regression models isolated the effect of time on performance holding other influential factors constant. RESULTS: Across all movements, loads, and times, PPmean was 235.2 ± 114.1 w; PPmax was 254.1 ± 120.0 w; PFDRmean was 1,036.1 ± 631.6 w/s; and PFDRmax was 1,243.4 ± 789.6 w/s. Differences in both PPmean and PPmax were detected by time of day (p<0.001) and load (p<0.001). The highest values were achieved between 2:00pm and 4:00pm. Similar relationships were found with time of day in PFDRmean (p<0.001) and PFDRmax (p<0.001). Holding constant the subject performing the set, arm dominance, exercise being performed, and the load applied, linear regression analyses found that if performance occurred between 2:00pm and 4:00pm, there was a 139.6 w/s increase in PFDRmean (95% CI: 75.5-203.6), 164.7 w/s increase in PFDRmax (95% CI: 79.7-249.8), 29.6 w increase in PPmean (95% CI: 20.7 ± 38.5), and 33.6 w increase in PPmax (95% CI: 24.4 ± 42.8). CONCLUSIONS: Success in many athletic contexts depends on expressions of power and the rate of its development. Our findings demonstrate diurnal rhythms in power parameters of the upper limb, with optimal performance occurring in the afternoon.

Link to Full Text

Share

COinS