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Arm and leg power output in swimmers during simulated swimming


Medicine & Science in Sports & Exercise: July 2000 - Volume 32 - Issue 7 - pp 1288-1292

SWAINE, I. L. Arm and leg power output in swimmers during simulated swimming. Med. Sci. Sports Exerc., Vol. 32, No. 7, pp. 1288–1292, 2000.

Purpose: Previously, it has not been possible to compare power output of the arms and legs during simulated swimming using dry-land ergometry. The purpose of this study was to determine arm-pulling and leg-kicking power using isokinetic dry-land ergometry.

Methods: Twenty-two highly trained male swimmers of mean (± SD) age, 23 ± 3.6 yr; body mass, 78 ± 5.9 kg; and stature, 1.79 ± 0.04 m were recruited to the study. First, subjects performed 10 s of all-out exercise at each of five resistance settings, with 1 h rest in between, to determine the best maximal pull velocity (MPVopt). Second, they performed an all-out 30-s test at MPVopt, which was repeated the following day. These repeated 30-s tests were performed separately using simulated front-crawl arm-pulling and leg-kicking, on a computer-interfaced swim bench and purpose-built leg-kicking ergometer. Peak and mean power output (PPO; MPO) were determined from regression analysis of the power vs time relationship.

Results: The mean (± SEM) PPO for arms and legs were 304 ± 22 W versus 435 ± 36 W. For MPO, the means were 225 ± 31 W vs 312 ± 26 W, respectively. These values were attained at mean MPVopt of 2.5 ± 0.2 m·s1 for arms and 2.3 ± 0.4 m·s1 for legs. The variation in PPO from repeated testing was 7.3% for arms and 8.3% for legs.

Conclusions: These results show that the legs can sustain greater power output than the arms during simulated swimming. Also, the intra-subject variation in measurement of power output is small using these dry-land ergometers. These methods of assessment might be useful in explaining swimming performance and in monitoring changes that take place during training.

Sport-specific assessment methods for power output of the arms and legs for swimming are poorly developed compared with other sports (1,23). Separate arm and leg power output measures would be useful in evaluating training programs and in understanding the importance of power output for swimming performance. The difficulties in assessing power output of the arms and legs during swimming arise from the absence of suitable transducers that can detect the force being exerted by the limbs. These difficulties are mainly due to continuous displacement of the water. Assessment of the power output of swimmers has therefore developed into two main methodological categories: water-based and dry-land ergometry.

The water-based methods have involved measurement of power using pressure pads (MAD system) (6), estimations of power output from cinematography (14), or determination of propulsive power from tethering devices (8). However, the MAD system cannot measure power output from the arms and legs separately. The accuracy of estimations from cinematographic techniques have been questioned (12). Furthermore, propulsive power, as measured in tethered swimming, differs significantly with power output of the limbs (21).

Because of the inadequacy of water-based techniques, attempts have been made to assess power output in swimmers using dry-land devices. These have included arm-cranking (4) and gym-based equipment (13). However, the most widely used dry-land device in swimming research has been the swim bench (13,15,20). In addition to being useful for measuring peak arm power, the swim bench is also used to assess critical power (16) and cardiopulmonary responses to incremental exercise (9,18). Although previously swim benches have only permitted measurements of arm movements and the specificity of the swim bench to swimming appears to be poor (11), this type of ergometer appears to be more suitable for swimmers than other ergometers.

Recently, it has become possible to measure power output during exercise that is similar to the front crawl leg-kicking action (17). An advantage is that the swimmer adopts a prone position on this ergometer similar to swimming. Also, it is possible to measure power during the upward and downward action of leg-kicking simultaneously. Because this leg-kicking device is an adaptation of the swim bench, it allows kicking-force, -distance, and -duration data to be stored and handled in a similar way to that used for arm-pulling (18).

Using cycle ergometry, accurate methods for determination of power output have been developed (1). These methods have been used to determine power output in athletes from various sports (19). The developments in cycle ergometry have included assessment of variation in measurement due to repeated testing (1). Procedures have been developed to optimize the force-velocity characteristics of the exercising musculature (10,22). However, none of these developments have been used in assessment of swimmers. Therefore, the purpose of this study was to establish reliable values for power output during all-out simulated front crawl arm-pulling or leg-kicking in swimmers using isokinetic dry-land ergometry.

Physiology of Exercise, De Montfort University Bedford, Bedford, UNITED KINGDOM

Submitted for publication March 1997.

Accepted for publication November 1997.

Address for correspondence: Ian L. Swaine, De Montfort University Bedford, 37, Lansdowne Rd., Bedford, MK40 2BZ, United Kingdom; E-mail:

©2000The American College of Sports Medicine