The Effect of Physical Fatigue on Lower Limb Functional Performance Tests in a Healthy Population

The Influence of Acute Physical Fatigue on Functional Performance Tests of the Lower Limb in a Healthy Population

The main objective of this project is: 1. To assess the influence of physical fatigue on a return-to-play test battery in a healthy population. In a later stage, these experiments could be carried out in a clinical context (e.g. in an ankle sprain population). The researchers will use a randomized, placebo controlled, counter-balanced, cross-over design. Twenty healthy subjects will visit the lab 3 times. On the first visit (familiarisation trial), the investigators will collect the participants' characteristics. The participants will also be familiarized to the procedures and materials of the experiment during this first visit. The second and third visit contain the experimental setup and will proceed as follows: first, the participants will fill in a pre-test checklist, a mental fatigue scale (M-VAS) and motivation scale. In the mean time a little blood will be collected from the ear lobe to determine lactate and glucose levels; also, blood pressure will be checked. Next, the subjects will carry out a functional test battery (hop test, vertical jump test, Y-balance test, and a balance reaction-time test). Session rate of perceived exertion (SRPE) is measured to indicate how fatigued the participants feel due to the test battery; also, M-VAS is collected once more, as well blood lactate, glucose and blood pressure. These measures are followed by either a physical fatigue inducing task (Modified 30 seconds Wingate protocol) or time-matched control task (sitting on the bike without pedalling). Afterwards, researchers will collect blood lactate, glucose and blood pressure two times more; participants have to fill in M-VAS (2x), perform the same test battery, and fill in the SRPE scale one more time. Heart frequency will be measured continuously during the trials.

Change in single-leg hop test for distance performance: from baseline and 20 minutes after baseline (immediately after the assigned interventions)

Change in vertical jump height performance: from baseline and 20 minutes after baseline (immediately after the assigned interventions)

Balance and reach performance; participants have to maintain their balance while reaching as far as possible along 3 different directions.

Change in Y-balance performance: from baseline and 20 minutes after baseline (immediately after the assigned interventions)

Balance and reaction time performance; participants have to maintain their balance while reacting as fast as possible in 3 different directions.

Change in balance and reaction time performance: from baseline and 20 minutes after baseline (immediately after the assigned interventions)

Change in M-VAS: at baseline, 10 min after baseline (immediately after the first test battery), 15 min after baseline (immediately after the assigned interventions) and 25 min after baseline (immediately after the final test battery)

Subjective measure of effort after completion of the test battery (scale from 0 to 10; 0 = very very easy; 10 = maximal effort)

Change in session RPE: at baseline (immediately after the first test battery), 15 min after baseline (immediately after the final test battery)

Subjective measure of motivation assessed with the self-reported Motivation scale of Matthews et al.. (the questionnaire measures 2 constructs: intrinsic motivation and task succes motivation;the questionnaire comprises 14 questions scored from 0 to 4 [0 = not all motivated, while 4 = maximally motivated]. Each construct contains 7 questions).

Capillary blood will be collected at the ear lobe for the determination of blood lactate (determined enzymatically)

Change in blood lactate: at baseline, 10 min after baseline (immediately after the first test battery), 15 min after baseline (immediately after the assigned interventions) and 25 min after baseline (immediately after the final test battery)

Capillary blood will be collected at the ear lobe for the determination of blood glucose concentration

Change in blood glucose: at baseline, 10 min after baseline (immediately after the first test battery), 15 min after baseline (immediately after the assigned interventions) and 25 min after baseline (immediately after the final test battery)

Change in blood pressure: at baseline, 10 min after baseline (immediately after the first test battery), 15 min after baseline (immediately after the assigned interventions) and 25 min after baseline (immediately after the final test battery)

Inclusion Criteria: Healthy (No neurological/cardiorespiratory/psychological/musculoskeletal disorders) Male and female No medication Non-smoker Between 18 and 35 years old Exclusion Criteria: Back and/or lower extremity injuries during the past 6 months Bone/joint abnormalities Dizziness, history of loss of consciousness, any inner ear disorders Nervous system disorders or dysfunctions Uncorrected eye disorders/dysfunctions Illness Use of medication or any kind of drugs Use of alcohol, caffeine and heavy efforts 24 hours before each trial Not eating the same meal the night before and the morning of each experimental trial