Statistical analysis

SPSS software (version 20, IBM, Chicago, IL) was used for all statistical analyses. An unpaired t test was performed to assess room temperature neuromuscular function of the young and old adults for the normal condition. A two-way ANOVA was performed to assess differences in peak tetanic force at 80-Hz stimulation, 80-Hz HRT, and passive and active eccentric force as a function of age and muscle temperature. A three way ANOVA was performed to assess changes in the eccentric to isometric ratio (ECC/ISO) and stiffness as a function of age, thumb adduction lengthening velocity and muscle temperature. When significance was observed, a post hoc analysis using t tests was performed with a Bonferroni correction to identify significant differences. The VA values were not normally distributed, and thus, a Mann-Whitney U test was employed for this particular variable. The level of significance for all tests was set at P ≤ 0.05. Tabulated and text data are presented as mean ± standard deviation (SD) and figure values as mean ± standard error (SE).