ANSLEY, L., P. J. ROBSON, A. ST CLAIR GIBSON, and T. D. NOAKES. Anticipatory Pacing Strategies during Supramaximal Exercise Lasting Longer than 30 s. Med. Sci. Sports Exerc., Vol. 36, No. 2, pp. 309-314, 2004.
Purpose: This study assessed whether pacing strategies are adopted during supramaximal exercise bouts lasting longer than 30 s.
Methods: Eight healthy males performed six Wingate anaerobic tests (WAnT). Subjects were informed that they were performing four 30-s WAnT, a 33-s, and a 36-s WAnT. However, they actually completed two trials of 30, 33, and 36 s each. Temporal feedback in the deception trials was manipulated so that subjects were unaware of the time discrepancy. Power output was determined from the angular displacement of the flywheel. The peak power (PPI), mean power (MPI), and fatigue (FI) indices were calculated for each trial.
Results: Power output was similar for all trials up to 30 s. However, at 36 s, the power output was significantly lower in the 36-s deception trial compared with the 36-s informed trial (392 ± 32 W vs 470 ± 88 W) (P < 0.001). The MPI was significantly lower in the 36-s trials (714 ± 76 W and 713 ± 78 W) compared with the 30-s trials (745 ± 65 W and 764 ± 82 W) although they were not different at 30 s (764 ± 83 W and 755 ± 79 W). The significant reduction in FI was greatest in the 36-s deception trial.
Conclusions: The significant reduction in power output in the last 6 s of the 36-s deception trial, but not in the 36-s informed trial, indicates the presence of a preprogrammed 30-s end point based on the anticipated exercise duration from previous experience. The similarity in pacing strategy suggests that the pacing strategy is centrally regulated.
For the last 30 yr, researchers have used the Wingate Anaerobic Test (WAnT), or a variant thereof, as a means of quantifying anaerobic performance in absolute terms of power output, which is then related to the maximum capacities of specific metabolic pathways. Traditionally the WAnT uses a 30-s cycle test protocol, performed against a constant force, in which subjects are instructed to cycle as hard as they can for the duration of the test. The three indices commonly derived from the WAnT are: i) peak power index (PPI), the highest power output obtained during the trial; ii) mean power index (MPI), the average power sustained over the duration of the trial; and iii) fatigue index (FI), the drop-off in power between the PPI and the final power output reading.
It was thought that during the initial 5-10 s of exercise energy is derived solely from alactic, phosphagenic pathways after which the metabolic fuel for the rest of the exercise bout is obtained from anaerobic glycolysis. Subsequent research has shown that, contrary to this belief, lactate accumulation begins within the first 10 s of supramaximal exercise (6) and that mitochondrial oxidative ATP synthesis increases almost immediately at the onset of exercise (24).
Despite this aerobic component of undetermined magnitude, the WAnT is considered to be largely dependent on anaerobic metabolism (27), and the associated fatigue has been mainly attributed to the fall in pH (10) that changes potassium concentration (8) and/or interferes with calcium release (1), impeding the ability of the muscle to contract (2) and resulting in selective fatiguing of the fast twitch fibers (5,15).
The WAnT may not have been designed to study muscle contractility or fatigue (4) but it has been suggested (13) that observing the effects of such all out efforts could provide insight into physiological and neuromuscular capabilities. Although this peripherally mediated fatigue might account for some of the drop-off in power output observed during the WAnT, EMG signal recordings have revealed a decline in iEMG activity toward the end of the test, which suggests the occurrence of central fatigue (17,30). Indeed, the fact that the fall in power in the Wingate test is explained by the falling cadence (19) can really only be explained by central, neural regulation because it is not clear how peripheral fatigue alone can produce the necessary changes in motor recruitment necessary to cause the progressive and marked reduction in cadence. Although the 30-s duration of the WAnT is generally considered optimal (12), a number of authors have suggested that it may not be sufficiently long to measure the total anaerobic capacity (9). The difficulty in extending the protocol beyond 30 s is the adoption of pacing strategies by subjects to ensure that they are able to complete the test (3,4). To prevent the adoption of such a conscious pacing strategy, it has been suggested that subjects should not be made aware of the elapsed time (20). More recently, the concept that subjects subconsciously pace themselves during exercise on the basis of prior experience has been developed (28,29).
There are a number of investigations into the competitive pacing strategies adopted during events lasting 1-6 min (11,14) and the optimal pacing strategies over these periods (18). However, to the authors' knowledge, no study has yet evaluated the possible presence of pacing during bouts of supramaximal exercise. The existence of a pacing strategy would suggest that substrate depletion or metabolic accumulation might not be the immediate cause of the power output profile during a WAnT.
Accordingly, the aim of this study was to determine whether deception and temporal manipulation could identify whether a subconscious pacing strategy exists during a standard and modified WAnT lasting between about 30 and 36 s.