Purpose: This dissertation study sought to examine the correlations of maximal handgrip strength (HGS), rate of HGS force development, and HGS fatigability on lean body mass, peak power, functional threshold power, and aerobic capacity in master’s aged cyclists and triathletes. Methods: A cross-sectional design was utilized and the analytic sample included n=31 master’s aged cyclists and triathletes (age: 49.1±10.4 years). Achievement motivation was self-reported with a Situational Motivation Scale Questionnaire. A stationary bicycle trainer and metabolic cart was used to evaluate peak power and aerobic capacity with standardized protocols. Whole body bioelectrical impedance measured lean body mass. An electronic handgrip dynamometer examined maximal HGS, rate of HGS force development, and HGS fatigability. Results: Maximal HGS was moderately correlated with peak power (r=0.46; p<0.01), lean body mass was moderately correlated with peak power (r=0.48; p<0.01) and negligibly correlated with aerobic capacity (r=0.37; p=0.04). Rate of HGS force development was also moderately correlated with peak power (r=0.36; p=0.04). Maximal HGS was moderately correlated with rate of HGS force development (r=0.63; p<0.01). Moreover, after ranking the measures, maximal HGS was moderately correlated with peak power (r=0.40; p=0.02) and lean body mass was moderately correlated with peak power (r=0.50; p<0.01). Conclusions: The findings from this dissertation study suggests that maximal HGS and rate of HGS force development share a signal with peak power in master’s aged cyclists and triathletes. Further, increased lean body mass is related to greater peak power. Maximal HGS and rate of HGS force development show promise for being utilized in a single protocol as a correlate for peak power when exhaustive testing is not possible, and maintaining lean mass is also advised for human performance in older endurance athletes.