Supervisors info:
Αθανασόπουλος Σ., Καθηγητής, ΤΕΦΑΑ, ΕΚΠΑ
Γελαδάς Ν., Καθηγητής, ΤΕΦΑΑ, ΕΚΠΑ
Κοσκολού Μ., Επίκουρη Καθηγήτρια, ΤΕΦΑΑ, ΕΚΠΑ
Summary:
Precooling is used as a method for increasing athletic performance in athletes , performing to play with high intensity, in an environment with a high heat load. The benefits of precooling have been widely studied and are mainly due to the reduction of body core temperature (Tc) and improvement of cardiovascular responses at least while performing prolonged exercise. Regarding the performance of short-term high-intensity exercise after precooling, the results are conflicting.
PURPOSE
The purpose of this study was to examine whether 30 minutes of whole body (at chest level with left arm and hand out of the water) immersion in water at 16-18oC can affect short-term performance (peak power output ) and dynamic balance ability.
METHOD
This study included 10 healthy male volunteers aged 18-26 years. To assess the short-term performance, volunteers performed a repeated intermittent sprint protocol (lasting 5 seconds each) in a mechanical cycloergometer and were also executed a shuttle run test 6x5 meters. Dynamic balance ability was tested by multiple single leg hop test procedure. In a first visit to the laboratory maximal oxygen uptake (VO2max) was determined and was performed familiarization of the subjects with the specific measurements of the experimental protocol. In the next two visits, volunteers executed the 2 experimental conditions with random and counterbalanced order, after a precooling (Pcool) intervention, and without it, in control condition (Contr). Initial test evaluation of dynamic balance ability and the shuttle run test (6x5 meters) performed in thermoneutral environment (19-22oC), while both protocols of repeated sprint in cycloergometer (Cisp) and the second test assessment dynamic balance ability, performed in a environmental chamber (temperature: 31-33o C, humidity: 40-50% rh). The performance in repeated sprint protocol of the cycloergometer was assessed by recording the peak power output per sprint(Pmax), the performance of the shuttle run test 6x5 meters was evaluated by measuring the total time to complete and the dynamic balance ability was assessed by recording the landing and balance errors, as well as on the total errors, which committed the volunteers while performing the test. Also in specific parts of the protocol recorded the body rectal temperature (Tre), the temperature of the finger (Tfin) and forearm (Tfarm), heart rate (Hr), thermal sensation(Ts) and perceived fatigue (Borg scale). The statistical analysis was performed using ANOVA for repeated measures (repeated measures) over time with a certain level of statistical significance to p ≤ 0,05 and performed using the statistical program STATISTICA 5.0.
RESULTS
In Pcool condition an increase in landing errors (p=0,051) and balance errors (p=0,036) and a significant increase in total errors (p=0,018) compared with the corresponding values in the Contr condition was observed. A reduction in Pmax (p ≤ 0,001), and in the shuttle run 6x5 meters test were also found to increase of time to complete tendency, but was not significant (p=0,064) in comparison to the corresponding values of Contr condition. The index values of vasoconstriction (Index) in Pcool condition was very high throughout the duration of the protocol with compared to the corresponding values in the Contr condition. Body rectal temperature (Tre) in Pcool condition, tended to be lower in Cisp test (p = 0,051), compared with the corresponding values in the Contr.
DISCUSSION-CONCLUSIONS
High balance errors and worse short-term performance observed in this study was probably due to dysfunction of neuromuscular system. Rising deficits of balance can possibly lead to the occurrence of musculoskeletal injuries in the early stages of exercise after application of this method of precooling and should be evaluated by the technical and medical staffs of the teams, if applicable.
