Characteristics of titin in strength and power athletes

The purpose of this investigation was to identify characteristics of the muscle protein titin in different athletic populations with increased levels of strength and power relative to non-athletes. Subjects fell into one of four groups: (1) non-athletes (NA) ( n=5), (2) weightlifters (WL) (n=5), (3) powerlifters (PL) (n=5), (4) sprinters (S) (n=5). A one repetition maximum in the squat exercise was performed to assess strength. In addition, countermovement vertical jump trials were performed to assess power capabilities. Peak power (W(peak)) was calculated for the vertical jumps from force plate measurements. From gel electrophoresis analyses of muscle samples, titin-1 (T1) and titin-2 (T2) protein bands were identified, quantified and expressed relative to each other. In addition the relative mobility (R(f)) of T1 and T2 was determined as an estimate of molecular weight. The NA group [%T1=47.8 (5.1), %T2=52.2 (5.1), mean (SE)] had lower T1 and higher T2 percentages than WL [%T1=62.3 (6.6), %T2=37.7 (6.6)], PL [%T1=66.8 (5.0), %T2=33.2 (5.0)] and S [%T1=65.9 (4.9), %T2=34.1 (4.9)] groups (P< or =0.10, preliminary investigation into titin and exercise justifies more liberal alpha level). No significant differences were found in R(f) of T1 or T2 between the groups. This investigation has shown that there is a differential expression of titin protein bands in competitive athletes with increased levels of strength and power in comparison to untrained non-athletic individuals. Some relationships between titin characteristics and athletic performance were observed; however, no conclusions can be made based on these data as to the contribution of titin to strength or power capabilities.