Effects of Prior Warm-up Intensity on Cycling Performance

Introduction
There is a common belief that warm-up contributes to Improved athletic performance (Bishop, 2003). Traditionally in competition/exercise a low-level activity will be performed before high intensity exercise is started. This is known as a warm up, warm ups are important to conduct as they can help prevent injuries. Warm ups raise body and muscle temperature; this helps prepare the body for strenuous activity. Many studies have established that there are several physiological changes that can occur in active warm-ups, these changes can be seen in some cases to improve overall performance, predominantly during high-intensity exercise activities. These studies show rises in heart rate (Andzel, 1978 & MacDonald et al, 1997), an acceleration in VO2 kinetics due to higher O2 availability to the muscles that are functioning at the beginning of exercise (Burnley et al, 2000 ; Gray et al, 2001 ; Delorey et al 2004). Alternatively, studies by Gerbino et al 1996 and Martin et al, 1977, found reductions in lactate accumulation.

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Studies conducted by Hampsen et al, 2001 and Howard et al, 1966 found conflicting results to those stated above. Their studies resulted in an active warm up not producing any substantial changes physiologically that would ultimately improve performance. Papers produced by Bishop, 2003 and Genovely et al, 1922 stated that If a warm up is too lengthy or the activity it too intense, this could make the performer begin exercise with conflicts in homeostasis or substrate depletion, these two factors can potentially mimic competition conditions around midway through an event and ultimately could lower performance levels.
Many studies suggested and found benefits of  passive and/or active warm ups for high intensity small duration resistance exercises (Bishop, 2003; Gray & Nimmo, 2001). Other studies do challenge this and look further into whether warm ups will greaten (Bishop, 2003), delay (Andzel et al,1982; Gregson et al, 2002), or simply have zero effect (Andzel & Gutin, 1976; Grodjinovsky, Magel, 1970) on long endurance exercise.
Asmussen & Boje, 1945, found most of the effects of warm up on performance have been seen to be due to temperature related mechanisms. Passive heating can allow an individual to gain an increase in their Muscle Temperature or core temperature levels, this can be reached by performing active warm up, and this lowers the depletion of energy substrates. Passive warm ups include raising muscle or core temperature manually, there are multiple methods which you can use to do this, for example Baths, Hot showers, Saunas and Heating pads have all be used in studies or in prior stages of competition.
Active warm ups have seen to help improve all short, intermediate and long term periods of exercise/performance. Enhancements in short term performance after active warm up is seen to increase highly though not totally due to increases in active muscles temperature. Possible mechanisms include decreased stiffness of muscles and joints, increased transmission rate of nerve impulses, an altered force-velocity relationship and increased glycogenolysis, glycolysis and high-energy phosphate degradation. An additional non-temperature-related mechanism may be decreased muscle stiffness by ‘breaking’ the stable bonds between actin and myosin filaments. However, short-term performance may be impaired if the warm-up protocol decreases the availability of high-energy phosphates as a result of being too intense or not allowing sufficient recovery before commencing the task.

Warm up also appears to improve long-term and intermediate performance if it allows the athlete to begin the subsequent task in a relatively non-fatigued state, but with an elevated baseline V̇O2. While it appears that warm-up exercise does not increase V̇O2 kinetics, warm up may allow subsequent tasks to begin with an elevated baseline V̇O2. Consequently, less of the initial work will be completed anaerobically, leaving more of the anaerobic capacity for later in the task. Long-term performance may be impaired if the warm up depletes muscle glycogen stores and/or increases thermoregulatory strain.
The general aim of this study was to assess the effect of a high intensity warm up and no prior warm up on overall performance in a 5-minute performance trial, assessing heart rate and rate of perceived excursion of participants throughout the trial. The main aim was to see if the performance of the individual after a high intensity warm up would deplete due to fatigue and other factors. Therefore, it was hypothesized that participants would perform better in the 5-minute performance trial when no prior warm up was performed.
Methods
After providing informed consent. 5 Male participants all studying Sport and Exercise Science in Aberystwyth University participated in this study. None of the participants had any previous experience in competitive cycling only what they would have gained in general activity/exercise. The 5 participants were aged 20-21 (Average age: 21±0.71), Participants Height (Average = 177.38 ± 4.65), Body Mass (Average = 78.24 ± 12.64) and Peak Power (Average = 257.8 ± 43.27) were calculated. This study was ethically approved by the Aberystwyth Ethical Committee.
The participants were to visit the laboratory once in 3 separate weeks for testing. In the first week, each participant’s peak power was to be found as this would be used as the Linear factor in the next part of testing. The participants peak power was found by using an Incremental RAMP test. In this test participants cycled for 3 minutes with no load, after the 3 minutes had passed the wattage increased by 2W per second. The participants were to cycle until failure, and their final power output reading was their peak power.
Before cycling participants were able to adjust seat height and the position of the handles to ensure they were in a comfortable position where they could perform to their best ability. The participants would either be conducting a high intensity warm up or no warm up at all before the performance trial, if in the first testing day they performed the warm up, the following week they would be doing no warm up. It was randomised to decide whether participants were conducting warm up or no warm up as this created a crossover trial. For the warm up, participants cycled at 70% of their peak power at 60 rpm for 5 minutes.
For the performance trial the bike (Lode Corival) was needed to be placed into linear mode. The bike was put into linear mode straight after the warm up was completed, giving the participant a low amount of rest time (< 1 minute). If the participant was conducting no warm up, then the bike would already be set and the participant would start straight away. For the performance trial, a starting load of 90% of participant’s peak power at 95 rpm was used, the participant was free to self-pace after the start of the trial. The participant was encouraged to produce an all-out effort, but to ensure it was evenly paced to make sure as much work as possible was completed during the 5 minutes. During the trial, the participant was allowed to view a running clock. During the trial, strong verbal encouragement was given to the participant, especially during the latter stages.
The Linear factor (90% of peak power) was calculated using this equation:
LF =    Power Output                  RPM2
Statistical Analysis
During each of the participant’s trials Power Output, Rate of Perceived Excursion (RPE) and Heart Rate were monitored at the first 5 seconds of the trial and then at every minute. These values were taken for both warm up and no warm up trials. Resting heart rate was taken before exercise. This data was all collected into an Excel Sheet (Microsoft, Redmond WA), after all data was collected means and standard deviation (SD) of participants scores overall were calculated. The completed data set was then transferred to SPSS (IBM, Sommers, NY). There a Parametric 2-Way Repeated ANOVA using the Bonferroni correction was used to test the data.
Results
The results found for the difference between the no warm up trial and warm up trial and the heart rate of the participant’s showed that there was no significant difference, F(1,4) = 7.29, p = 0.54, but when looking at this value it was not far off being significant. There was a significant difference found between heart rate readings at different times during the trials, F(1.28,5.12) = 152.38, p = <0.001. There was a significant difference found in trial*time, F(2.25,9.02) = 7.31, P = 0.012.
The results from analyzing the difference between the no warm up and warm up trials and power output scores found no significant difference, F(1,4) = 0.06, P = 0.83. The results for the variance between power output readings and the different time intervals looked at shows that there was a significant difference, F(2.08,8.31) = 6.94, p = 0.02. The post hoc test performed using the Bonferroni correction showed that there was no significant difference from any of the times used and the power output made, P = 1.00. There was also no significant difference found in the trial*time, P = 0.54.
The results showing if there was a significant difference between the trial and the Rate of Perceived Excursion (RPE), showed a significant difference, F(1,4) = 31.42, P = 0.01. The post hoc test performed with the Bonferroni correction showed that there was an average increase of 2.93 RPE from No warm up trial compared to the warm up trial (P=0.01). There was a significant difference shown also in the different time stages and the RPE, F(1.36,5.45) = 58.75, P<0.001.
Figure 1: The means and standard deviation of heart rate along the different time points for both No warm up (Orange Line) and Warm Up (Blue Line).
Figure 2: The means and standard deviation of Power Output along the different time points for both No warm up (Orange Line) and Warm Up (Blue Line).

Figure 3: The means and standard deviation of Rate of Perceived Excursion along the different time points for both No warm up (Orange Line) and Warm Up (Blue Line).
Discussion
The aim of this present study was to look into the effect of warm up intensity on a 5 minute performance trial while assessing RPE, Heart Rate and Power Output. It was hypothesized that compared to having no warm up prior to the performance trial, there would be a depletion in participants cycling performance in the performance trial after a high intensity warm up was conducted.
With regards to the results found for RPE, the hypothesis can be accepted. The RPE results found a significant difference between the different trials and the RPE. RPE increased towards the end of the warm up trial, this shows that the participant was finding it much harder to cycle at a strong power output and ultimately this could be a factor that would decrease overall performance in the latter stages. A you can see in Figure 3 there was a steady increase of RPE in both trials as the time went on, the trial with warm up shows a much higher RPE level to start with and this is a continued trend over the length of the trial. This clearly shows in this study that the Warm Up Trial did affect the participant’s in a way. Authors such as Johnson (2014) and Cheng (2007) stated that they thought a higher response of RPE during a warm up was due to an increase in motivation and participant’s effort when performing an active warm up. They proposed that some participants may use the warm up period to mentally prepare for the upcoming performance trial/activity. Bishop (2003) added to this by reporting that he thought if a warm up is not present the psychological preparation time while warming up is nonexistent and this could potentially have an impact on a participant’s performance.

When looking at peak power this hypothesis was rejected due to no significant difference being found between power output and the different trials. Although there was a significant difference found between power output and time, when a post hoc test was completed it was found that there was no significant difference among the time trials. As seen in Figure 2 there is not much visible difference in the two trials over time in graph form, they both follow a very similar pattern. Findings in other papers that contradict or back up this study may be because of differences in the performance parameters studied (For eample: Exercise duration to exhaustion against peak power). It is likely that any abrupt benefit of warming up on power output reading may be overruled by the time of the exercise.
When looking at the findings of the relationship of the two different trials and heart rate, no significant difference was found, although the significant difference was not far away from being significant.  On the other hand, there was a large significant difference found between heart rate and the different time frames. As presented in Figure 1 there is difference shown in heart rate scores for the trial with warm up compared to the trial without against time. With both sets of data showing a similar pattern of peaking, but hear rate for the warm up trial is at a much higher level. Another study by Gray and Nimmo (2001), found that there was a significant difference in heart rate in warm up trials and no warm up trials. They found a difference in heart rate levels in an Active warm up and no warm up with the warm up trials hear rate scores being much higher. Bishop et al 2003 found there were no significant differences in heart rate between 2 conditions at any time.
A lot of previous studies in this field use muscle temperature as a factor when looking at performance and peak power. The outcomes of enhanced muscle temperature on performance during high intensity dynamic activity of short duration exercise has been investigated. When studies have used local passive warm ups to increase muscle temperature, there is either an enhancement (For example in a study by Sargeant, 1987) or there is no positive effect that occurs (shown in a a study by Davies and Young, 1983) on subsequent short term power output. When exercise is instantly performed after conducting a low intensity active warm up (around 30-60% of V02max), it has been found that maximal peak power and also a participant’s time to exhaustion are heightened. While on the other hand, after a high intensity warm up is completed (around 70-100% of VO2max), there is a depletion in these performance factors shown (De Bruyn-Prevost and Lefebvre, 1980; Sargeant and Dolan, 1987).
Andzel (1978) conducted a study on the effects of warm up and no warm up and also varied rest times between warm up and a treadmill performance activity. The rest periods used in this study were 30, 60, 90, and 120 seconds. The rest period of 30 seconds was found to produce the best performance from participants. Andzel suggested that the short rest period may have been most useful in allowing any lactate formed when conducting the warm up to be cleared away, as well as go through at least limited resynthesis of phosphagens.

A limitation of this study would be the judging the participant’s efforts throughout the performance trial. Although participants were told to perform an all-out effort in the performance trial, they were allowed to self-pace to ensure that they completed the trial. The self-pacing could be taken lightly by some participant’s and this could lead to them not putting in maximum effort and ultimately not becoming completely exhausted. This is a major limitation as it could affect the results massively and could provide untrue data. In this study a larger pool of participants could be used to help solidify results, alternatively using a precise population could yield better results and set a researcher up for a more in depth analysis (e.g. Gender, Specific Sporting Teams/Level). As mentioned in the introduction of this study there is also passive warm ups, this could also be looked at if a bigger time frame was used for testing, this could have made for a larger amount of results and could have identified significance in different places. One more limitation could be the use of the peak power test, as this can go on for a while some participant’s may have work until complete exhaustion, which would leave their peak power value untrue. The Wingate Test could alternatively be used as a quicker less time consuming test to find peak power.
References 

Bishop, D. (2003a). Warm up I: potential mechanisms and the effects of passive warm up on exercise performance. Sports Med, 33 (6), 439–454.

Asmussen E, Boje O. Body temperature and capacity for work. Acta Physiol Scand 1945; 10: 1–22

3. BISHOP,D. Warm Up II. Performance changes following active warm-up and how to structure the warm-up. Sports Med. 33:483- 498,2003.

Susan Gray & Myra Nimmo (2001) Effects of active, passive or no warm-up on metabolism and performance during high-intensity exercise, Journal of Sports Sciences, 19:9, 693-700