Front Crawl

"This study attempted to establish whether an optimal age could be identified at which children were ready to learn the front crawl swimming stroke. The variables examined were: the number of lessons, the age of commencing lessons and the time duration for learning to swim l0m front crawl (Level 3).
Longitudinal records of 326 children, aged between 2 and 8 years, were analysed using General Linear Model two-way (Age x Sex) analysis of variance procedures. The main effect for age was significant (p<0.001) for all three variables. Post hoc analysis revealed that the children who started at 5 years of age received signiftcantly fewer number of lessons and took shorter
duration compared to those who commenced leaming to swim at an earlier age. Whether pupils started lessons at 2, 3 or 4 years of age, they achieved Level 3 at approximately the same mean age of 5 1/2 years. The optimal readiness period was identified in this study to be between 5 snd 6 years of age. There was little evidence of gender differences for all three variables."

The aims of this study were (1) to evaluate changes in muscle activity associated with physiological fatigue and decreased swimming velocity (SV) during 200 m of front crawl swimming, and (2) to examine the relationship between the decreased SV and changes in kinematic or electromyogram parameters. Twenty swimmers participated in a 4 × 50-m swim test. The surface EMG of 11 muscles (7 in the upper limbs and 4 in the lower limbs) was measured and the mean amplitude value (MAV) for one stroke cycle was obtained. The SV and arm angular velocity (AAV) of shoulder flexion during the first (early stroke) and second (late stroke) half of the underwater arm stroke were analyzed using an underwater camera. The AAV, the MAV of flexor carpi ulnaris (FCU), biceps brachii (BB), and triceps brachii during the early stroke, and the MAV of rectus femoris decreased along with a decrease in SV. In contrast, the MAV of the pectoralis major (PM) increased significantly in the final 50 m. The rate of change in MAVs (ΔMAVs) of FCU, BB and latissimus dorsi during the early stroke, and ΔMAV of biceps femoris were significantly correlated with ΔSV and/or ΔAAV. Positive correlations were identified between ΔMAVs of several muscles. However, no negative correlations were observed between ΔMAVs. These results suggest that the decrease in SV was related to decreases in the activities of several muscles that coordinated with each other, and that a compensating strategy occurred between PM and other muscles in the final 50 m.

Male (n = 25) and female (n = 14) competitive swimmers were studied during tethered (breaststroke) and free (front crawl) swimming to determine the validity of calculating exercise oxygen uptake (VO2) from expired gas samples taken immediately after the activity. Based on a single 20-s recovery VO2, the swimmers&amp;#39; VO2 max was correlated with performance in a 400-yd (365.8-m) front crawl swim. The best predictors of VO2 max for trained swimmers were lean body weight and stroke index (r = 0.97). The single best predictor of performance in the 365.8-m front crawl swim was the distance per stroke (r = 0.88), whereas the combination of distance per stroke and VO2 max (ml/kg LBW/min) correlated 0.97 with performance in the swim. This study demonstrates that it is possible to accurately determine the VO2 during maximal and submaximal swimming using a single, 20-s expired gas collection taken immediately after a 4-7 min swim. These findings demonstrate the importance of stroke technique on the energy cost and variations in performance during competitive swimming.