Does muscle fatigue influence swimming performance?

Introduction

Fatigue is a general concept intend to denote an acute impairment in the performance that includes, an increase in the perceived effort (1) and an inability to produce force (1, 3), that may cause decrease on motor performance (2). Purpose
Determine the influence of lower limbs muscle fatigue upon swimming performance (SP) in adult subjects.

Methods

We evaluated ten male athletes (21.40  2.01 years old) with 11.45  7.06 years of practice. Anthropometric body weight (77.22  10.52 kg), height (181.88  7.56 cm) and body fat (12.57 %) variables were measured. Swimming performance was determined during 50 meters crawl style swimming with criteria of time to swim first 25 meters (0 - 25 meters; T1); from 25 - 50 meters (T2) and total swimming time (0 - 50 meters / T1 + T2 (TT). Maximal legs workout was determined by maximal consecutive jumps test on an electronic force platform with relative times found at T1, T2 and TT. Results of number (NJ1, NJ2 and NJT) and height of jumps (HJ1, HJ2 and HJT), and muscle power (MP1, MP2 and MPT) to each swimming partial time were assessed

Results

We found average values of swimming to T1 = 12.6  1.0 seconds, T2 = 15.4  1.8 seconds and TT = 28.0  2.8 seconds, and the respective number of jumps to same time was (NJ1 = 15  2 jumps, NJ2 = 16  4 jumps, and NJT = 31  6 jumps) and height of jumps (HJ1 = 36.2  7.4 cm, HJ2 = 32.9  6.5 cm and HJT = 34.5  6.9 cm). Muscle power to same time was MP1 = 472.0  151.4 kg.cm.min, MP2 = 496.6  169.2 kg.cm.min and MPT = 966.8  313.7 kg.cm.min.

Discussion/ Conclusions

Fatigue analyses presented significant (p<.05) increased in T2 (18%) and NJ2 (8%) and significant decrease in HJ2 (10%). However, no significant change was found to MP2. On the other hand, we have found moderate and positive correlations values between percent fatigue in SP and NJ (.61), SP and HJ (.78*), as well as SP and MP (.59). These results indicated that muscle power presented similar values in MP1 and MP2, besides fatigue increase. It could be
explained by the increase on number of jumps and decrease on jumps height. Thus data allowed us to suggest that 1) swimmers reached muscle power plato, besides fatigue increase, 2) it seems that MP plato was kept due to higher movement velocity and low strength output at every each movement. Also, higher movement velocity would increase the drag, and decrease the swimming performance (2)

Conclusion

The data allowed us to conclude that maximal strength, or strength plato output during repeated contractions, seems to be more important to swimmers muscle power.

References

[1]. Enoka, R.M., & Stuart, D.G. (1992), J. Appl. Physiol. 72(5): 1631-1648.
[2]. Maglischo, E.W. (1999), Nadando Ainda Mais Rápido, Sao Paulo, Manole.
[3]. Klass M., Guissard N., & Duchateau J. (2003), J. Appl. Physiol. In Press 72(5), 1631-1648