The Effects of Passive Simulated Jogging on Parameters of Explosive Handgrip in Nondiabetics and Type 2 Diabetics: A Single Arm Study

Abstract

Aims. Type 2 diabetes (T2D) is associated with sarcopenia and decreased muscle strength. Explosive and isometric voluntary handgrip strengths (EHGS and HGS) are frequently utilized methods to ascertain health status and a marker of overall muscle strength. We have previously shown that a portable, motorized device, which produces effortless, rapid stepping in place (passive simulated jogging device (JD)), improves glucose homeostasis. This study quantitatively evaluated the effects of JD in modifying parameters of the modified EHGS curve in T2D and nondiabetic (ND) subjects. Methods. Twenty-one adult participants (11 ND and 10 T2D) (mean age: $41.3\pm 13.5$  yr) performed a modified explosive handgrip strength (EHGS) test on study day 1 followed by daily use of JD (90 min per day) for 7 days. The EHGS was repeated after 3 and 7 days’ use of JD (JD3 and JD7) and 3 days after completion of JD (Carryover). EHGS curves were analyzed for the following: maximal peak force value (MAX); rate of force development at 25%,75%, and 90% of maximum force; and maximum force (RFD25%, RFD75%, RFD90%, and RFDmax); time to 90%, 75%, and 25% of maximal force ( $t_{90},t_{75},t_{25}$ ) and time to maximal force ( $t_{\max }$ ); and the integrated area under the curve for force vs. time until task failure (iAUCTF); and fatigue resistance times at 50% and 25% of maximal force (FR50 and FR25) and fatigue resistance time to task failure (FRTF). Results. At baseline, T2D had lower MAX compared to ND. There were no differences at baseline for force development time or fatigue resistance time between T2D and ND. In both T2D and ND, 7 days of JD increased FR25 and FRTF and iAUCTF compared to baseline. Conclusion. JD for at least 7 days prior to EHGS increased time to task failure (fatigue resistance) and iAUCTF of the force-time curve. JD is a reasonable intervention to decrease sedentary behavior and improve muscle fatigue resistance under various clinical and nonclinical scenarios. This trial is registered with NCT03550105 (08-06-2018).