Energy cost and intracyclic variation of the velocity of the centre of mass in butterfly stroke

Abstract

The purpose of this study was to examine the relationship between the intra-cycle variation of the horizontal velocity of displacement (dV) and the energy cost (EC) in butterfly stroke. Five Portuguese national level swimmers performed one maximal and two sub-maximal 200-m butterfly swims. The oxygen consumption was measured breath-by-breath by portable metabolic cart. A respiratory snorkel and valve system with low hydrodynamic resistance was used to measure pulmonary ventilation and to collect breathing air samples. Blood samples from the ear lobe were collected before and after each swim to analyse blood lactate concentration. Total energy expenditure ( E (tot)) and EC were calculated for each swim. The swims were videotaped in the sagittal plane with a set of two cameras providing dual projection from both underwater and above the water surface. The APAS system was used to analyse dV for the centre of mass. The E (tot) increased linearly with the increasing V, presenting a significant correlation coefficient between these parameters ( r =0.827, P <0.001). The increase in EC was significantly associated with the increase in the dV ( r =0.807, P <0.001). All data were presented as the mean value and the standard deviation. It is concluded that high intra-cycle variation of the velocity of the centre of mass was related to less efficient swimming and vice versa for the butterfly stroke.

Arm coordination, power, and swim efficiency in national and regional front crawl swimmers

“…The cut-off frequency was set at 6 Hz. The IVV was analyzed by calculating its coefficient of variation (CV) (Alberty, Sidney, Huot-Marchand, Hespel, & Pelayo, 2005;Alves et al, 1996;Barbosa et al, 2005;Miller, 1975;Schnitzler et al, 2008) Then, according to Toussaint et al (2006), the efficiency of propulsion generation (e pg ) of the arm stroke was the v²/u² ratio, assuming that v² is proportional to the drag force and u² is proportional to the propulsive force. When the swimming speed increased, assuming that propulsive force increases with drag force, the e pg should remain constant.…”

“…Therefore, to accurately measure efficiency, an estimation of the extra power output wasted with IVV is required (Miller, 1975;Nigg, 1983). Generally, higher IVV has been correlated to an increased rate of the energy expenditure of swimming (Alves, Gomes-Pereira, & Pereira, 1996;Barbosa et al, 2005Barbosa et al, , 2006 caused by a power term related to the acceleration and deceleration of the center of gravity. Notably, Nigg (1983) predicted that a speed change of 10% within a stroke cycle resulted in an additional work demand of about 3%, suggesting that the best solution to increase the capacity to produce propulsive forces while minimizing power output seems to be to reduce IVV.…”

Validation of the New Visual Swimming Pace Control System in Real-Time

“…This is made possible with the help of a stabilized swimming speed, which lowers the physiological cost incurred during exercise (Barbosa et al, 2005). Controlling and maintaining the desired swimming speed helps conserve energy required in order to perform the exercise.…”

Physical Activity in the Water Accompanied by Music

“…Therefore, the search for methods that drive positive changes in human behavior, manifested in an active leisure time in the aquatic environment, is of prime importance. To date, most of the activities associated with this dilemma have focused on improving movement techniques to enhance the efficiency of swimming [14,15].…”