4000-m Time Trials Research Articles

Deceptively-Altered Visual Feedback Alters 4km Cycling Time Trial Performance in Trained Cyclists

Introduction The brain maintains a performance reserve capacity by regulating fuel utilization. One method of overriding the governor is the utilization of deception. The purpose of this study is to examine the effect of deceptively-modified feedback on time to completion during a laboratory based 4000m time trial.  Methods 12 trained cyclists (8 Male, 4 Female) age 41.6 ±12.3 years with a mean peak aerobic capacity of 51.3±6.5ml/kg/min. Participants completed a VO 2 peak test followed by two baseline 4km time trials without the influence of a virtual avatar competitor. The participants completed two more time trials in randomized order competing against an avatar representing 100% (control) or 102%(deception) of their fastest baseline trial. Participants were told that they were competing against their previous fastest baseline trial during time trials 3 and 4.  Results Time to completion during the deception condition was shorter than the control condition -3.62±0.8sec p=.004 95% CI [-5.99, -1.24]. Average power output was greater during the deception trial compared to the control trial 7.1±2.28w p=.033 95% CI [0.55, 13.66]. Power output was greater during the deception trial at 30% and 40% of the trial compared to the control trial 12.0±2.4w p=.001 95% CI [5.36, 18.6] and 12.4±2.5w p=.001 95% CI [5.5, 19.4]. Rating of Perceived Exertion was lower during the first 25% of the deception trial compared to the control -1±.348 p=.046 95% CI [-1.98, -.018].  Discussion and Conclusions It is possible a lower RPE during the first 25% of the time trial allowed for increased power output during the middle portion of the deception trial. The increased power output could have led to the improved time to completion in the deception trial.

Metabolic consequences of β-alanine supplementation during exhaustive supramaximal cycling and 4000-m time-trial performance.

The present study investigated the effects of β-alanine supplementation on the resultant blood acidosis, lactate accumulation, and energy provision during supramaximal-intensity cycling, as well as the aerobic and anaerobic contribution to power output during a 4000-m cycling time trial (TT). Seventeen trained cyclists (maximal oxygen uptake = 4.47 ± 0.55 L·min(-1)) were administered 6.4 g of β-alanine (n = 9) or placebo (n = 8) daily for 4 weeks. Participants performed a supramaximal cycling test to exhaustion (equivalent to 120% maximal oxygen uptake) before (PreExh) and after (PostExh) the 4-week supplementation period, as well as an additional postsupplementation supramaximal cycling test identical in duration and power output to PreExh (PostMatch). Anaerobic capacity was quantified and blood pH, lactate, and bicarbonate concentrations were measured pre-, immediately post-, and 5 min postexercise. Subjects also performed a 4000-m cycling TT before and after supplementation while the aerobic and anaerobic contributions to power output were quantified. β-Alanine supplementation increased time to exhaustion (+12.8 ± 8.2 s; P = 0.041) and anaerobic capacity (+1.1 ± 0.7 kJ; P = 0.048) in PostExh compared with PreExh. Performance time in the 4000-m TT was reduced following β-alanine supplementation (-6.3 ± 4.6 s; P = 0.034) and the mean anaerobic power output was likely to be greater (+6.2 ± 4.5 W; P = 0.035). β-Alanine supplementation increased time to exhaustion concomitant with an augmented anaerobic capacity during supramaximal intensity cycling, which was also mirrored by a meaningful increase in the anaerobic contribution to power output during a 4000-m cycling TT, resulting in an enhanced overall performance.

Effects of Deception on Exercise Performance

The aim of this study was to investigate whether it was possible to reduce the time taken to complete a 4000-m cycling time trial by misleading participants into believing they were racing against a previous trial, when, in fact, the power output was 2% greater. Nine trained male cyclists each completed four 4000-m time trials. The first trial was a habituation and the data from the second trial was used to form a baseline (BL). During trials 3 and 4, participants raced against an avatar, which they were informed represented their BL performance. However, whereas one of these trials was an accurate (ACC) representation of BL, the power output in the other trial was set at 102% of BL and formed the deception condition (DEC). Oxygen uptake and RER were measured continuously and used to determine aerobic and anaerobic contributions to power output. There was a significant difference between trials for time to completion (F = 15.3, P = 0.00). Participants completed DEC more quickly than BL (90% CI = 2.1-10.1 s) and ACC (90% CI = 1.5-5.4 s) and completed ACC more quickly than BL (90% CI = 0.5-4.8 s). The difference in performance between DEC and ACC was attributable to a greater anaerobic contribution to power output at 90% of the total distance (F = 5.3, P = 0.02, 90% CI = 4-37 W). The provision of surreptitiously augmented feedback derived from a previous performance reduces time taken for cyclists to accomplish a time trial of known duration. This suggests that cyclists operate with a metabolic reserve even during maximal time trials and that this reserve can be accessed after deception.

Vo2 Reponse In Supra-maximal Time Trial Exercise.

PURPOSE: Limited research has been done on VO2 kinetics of time trial exercise in the supra-maximal domain or during free range exercise typical of competition. The hypothesis that VO2 response reaches a maximal amplitude and time constant in supramaximal time trial exercise and was not influenced by subsequent changes in power output (PO) was tested. METHODS: 8 well-trained cyclists performed a 1-min incremental exercise test to obtain maximal power output (Pmax), a 1500m (∼125%Pmax) and a 4000m (∼100%Pmax) cycle ergometer time trial (TT). Athletes were instructed to finish in as short time as possible, with an even-paced strategy. VO2 was measured breath-by-breath and modeled double-exponentially (4000m) or mono-exponentially (1500m). RESULTS: Pmax at the incremental test was 383.2 ± 26.6 W. VO2max at the incremental test was 4.52 ± 0.24 l/min. Mean PO was higher in the 1500m TT compared to the 4000m TT (479.3 ± 27.1 W; 378.0 ± 31.9 W). Both trials were characterized by an initial burst in PO during the first 15s (150.5 ± 14.2 %Pmax; 139.8 ± 10.0 %Pmax). No significant differences in VO2 primary response above baseline between trials were found for amplitude (3.45 ± 0.29 l/min; 3.52 ± 0.36 l/min) and time constant τ (10.8 ± 3.3 s; 11.4 ± 2.6 s). The primary component of VO2 kinetics of the 1500m did not differ from that in the 4000m time trials, despite large differences in PO. Maximal VO2 attained during the time trials was highest for the 4000m, caused by a gradual increase in VO2 over time during the trial (4.40 ± 0.26 l/min; 4.55 ± 0.18 l/min), but this difference was only ∼0.15 l/min. CONCLUSIONS: VO2 kinetics followed the same profile for 1500m and 4000m TT, independent of mean PO. VO2 response reached a maximal amplitude and time constant, which were not influenced by subsequent changes in PO. Near maximal values of VO2 can be reached within 2 minutes of strenuous exercise. The initial burst of PO characteristic for time trial exercise seems to be of importance to trigger the aerobic system maximally and might explain differences with the literature studying square wave exercise.

Relationship Between Power Output And iEMG In Differently Paced 4000-m Cycling Time Trials

Recent studies have investigated neuromuscular activity during bouts of high intensity exercise (St. Clair Gibson et al., 2001; Kay et al., 2001; Ansley et al. 2004) using measurements of the iEMG of the rectus femoris (RF) muscle. They have suggested the presence of a central control mechanism which allows completion of the activity without the development of physiological damage or premature fatigue. This suggestion is supported by observations that iEMG changes in parallel with power output (St. Clair Gibson et al., 2001; Ansley et al., 2004). PURPOSE The present study investigated the influence of different pacing strategies on neuromuscular activity and power output during 4000-m cycling time trials. METHODS Based on the results of a familiarization trial (FA), 8 male cyclists performed an even paced 4000-m time trial (EVEN), a 'submaximal first half' 4000-m time trial (SUB) and a 'supra-maximal first half' 4000-m time trial (SUPRA) in random order. In the SUB trial, the subjects rode the first 2000-m 5% slower than in the FA trial. In the SUPRA trial, they cycled the first 2000-m 5% faster. The remaining 2000-m of the SUB and SUPRA trials, subjects tried to finish as fast as possible. iEMG of the RF, vastus lateralis (VL) and biceps femoris (BF) muscle was measured during the time trials, as was power output (PO). RESULTS In the SUB trial, PO increases in the second half of the race (283.2W vs. 347.4W, p = 0.00). In the EVEN trial, PO remained constant (333.7W vs. 318.4W, p = 0.12) and in the SUPRA trials, PO decreased (355.0W vs. 297.0W, p = 0.00). In contrast to this, in all muscles, an increase in iEMG over the course of the time trial was found in all conditions. Only for the RF muscle in the EP condition, this was not the case (see figure).FigureCONCLUSION Our data do not support the suggestion that iEMG decreases in all muscles during time trials when PO is decreasing. This was evident only in the RF. As such, our data do not support the hypothesis of a central governor.

Relationship Between Power Output And iEMG In Differently Paced 4000-m Cycling Time Trials

Recent studies have investigated neuromuscular activity during bouts of high intensity exercise (St. Clair Gibson et al., 2001; Kay et al., 2001; Ansley et al. 2004) using measurements of the iEMG of the rectus femoris (RF) muscle. They have suggested the presence of a central control mechanism which allows completion of the activity without the development of physiological damage or premature fatigue. This suggestion is supported by observations that iEMG changes in parallel with power output (St. Clair Gibson et al., 2001; Ansley et al., 2004). PURPOSE The present study investigated the influence of different pacing strategies on neuromuscular activity and power output during 4000-m cycling time trials. METHODS Based on the results of a familiarization trial (FA), 8 male cyclists performed an even paced 4000-m time trial (EVEN), a 'submaximal first half' 4000-m time trial (SUB) and a 'supra-maximal first half' 4000-m time trial (SUPRA) in random order. In the SUB trial, the subjects rode the first 2000-m 5% slower than in the FA trial. In the SUPRA trial, they cycled the first 2000-m 5% faster. The remaining 2000-m of the SUB and SUPRA trials, subjects tried to finish as fast as possible. iEMG of the RF, vastus lateralis (VL) and biceps femoris (BF) muscle was measured during the time trials, as was power output (PO). RESULTS In the SUB trial, PO increases in the second half of the race (283.2W vs. 347.4W, p = 0.00). In the EVEN trial, PO remained constant (333.7W vs. 318.4W, p = 0.12) and in the SUPRA trials, PO decreased (355.0W vs. 297.0W, p = 0.00). In contrast to this, in all muscles, an increase in iEMG over the course of the time trial was found in all conditions. Only for the RF muscle in the EP condition, this was not the case (see figure).FigureCONCLUSION Our data do not support the suggestion that iEMG decreases in all muscles during time trials when PO is decreasing. This was evident only in the RF. As such, our data do not support the hypothesis of a central governor.