There are some recent student projects that have been done in the Human Performance Laboratory. Click on the name of the project to view the abstract or full text.
 
 

Common injuries seen in an athletic population range from strains, ligament sprains, dislocations and ruptures.  Injury prevention is a major component of Athletic Training and Physical Therapy.  Flexibility is a factor frequently thought of when working with athletes on injury prevention and rehabilitation.  Flexibility can be defined as the range of motion of a joint or series of joints that are influenced by muscles, ligaments, tendons or bone.  Flexibility is also influenced by the type and level of activity performed, gender, age, genetics, temperature and the joint being evaluated.  Muscles possessing greater extensibility are less likely to be over-stretched during vigorous activity and to have delayed onset muscle soreness.  Flexibility is also thought to aid in athletic performance.  Activities such as golf and tennis require sufficient shoulder, trunk and hip flexibility for optimal performance.  It is generally accepted that the more flexible an athlete is the less susceptible to injury they are.  Data has suggested that flexibility demonstrate a significant U-shape relationship with the incidence of injury.  It has shown subjects at both extremes are more at risk than the average.

The purpose of this study is an attempt to determine whether flexibility plays a significant role in musculoskeletal injury.  This questions remains equivocal in the literature with numerous studies that report conflicting findings.  Some studies show that flexibility prevents injury while other studies show that flexibility can increase the incidence of injury.  Several studies have found the date to be inconclusive.  Athletes participating in various sports will demonstrate a wide range of flexibility measures, as the flexibility demands of specific sports vary widely.  Furthermore, the injury rate among female athletes is higher than their male counterparts.  One possible explanation may be the increased flexibility found in females.  The current study is concerned with flexibility requirements and the differences between males and females across all sports.  It is the specific intention of this study to answer whether or not athletes with excessive flexibility are actually at increased risk for musculoskeletal injury.  We propose to look at both the male and female athletic population.

Recently there have been numerous studies looking at the relationship between strength and force-velocity movements.  In this study the relationship between isokinetic leg strength and vertical jump score was determined.

Fifteen male volunteers between the ages of 18 to 25 years of age participated in this study.  Two separate measurements were taken and statistically analyzed using Pearsonís product moment correlation coefficient to determine if a relationship exists between the two measurement variables.  Measurement one consisted of the average mean of three trials of a two-legged standard vertical jump.  Measurement two consisted of the mean average of five trials of peak torque of isokinetic leg strength.

Using Pearsonís product moment correlation coefficient a correlation coefficient of .006 at alpha level <.05 was determined.  It was concluded from this study that there is no relationship between isokinetic leg strength and vertical jump score.

Keywords:  strength, isokinetic, peak torque, vertical jump, correlation coefficient

Thirty-one male athletes and thirty-two female, uninjured subjects had electromyographic testing of the peroneal longus and brevus, tibialis anterior, and gastrocnemius in response to inversion and dorsiflexion perturbation using a hydraulically controlled tilt platform.  Subjects went through one session of testing that consisted of five consecutive left ankle inversion trials, five consecutive left ankle dorsiflexion trials, five consecutive right ankle inversion trials, and finally five consecutive right ankle dorsiflexion trials.

The data was then separated by gender and the latency times and muscle recruitment orders were analyzed.  There were some significant differences between male and female reaction times but no data that showed these differences were consistent across muscle groups for either inversion or dorsiflexion.  Muscle recruitment order also showed similar results.  The data shows that both males and females recruit the gastrocnemius, then the tibialis anterior, and finally the peroneal longus in response to right and left ankle inversion.  Although this pattern was shown no differences in muscle recruitment order was  found between males and females.

My results show that there are not gender differences in lower leg muscle activity in response to ankle inversion or dorsiflexion perturbation.

This study compared the flexibility and strength scores obtained from a LIDO isokinetic dynamometer (Chattanooga, Tennessee) of twenty (N=20) Division 1 female athletes.  Each subject completed a five-minute warm-up on a stationary bicycle, riding at a submaximal speed.  After each subject had completed the warm-up, they were then measured for hamstring flexibility (degrees) using the straight leg raise (SLR).  Both legs were measured for hamstring flexibility.  Upon completion of the SLR, each subject was measured for strength on the dynamometer.  Raw scores from the dynamometer (NM) were then correlated against the flexibility scores to find the Pearson Product Correlation (P < 0.05).  The procedure was repeated for both legs.  Peak torque to body weight ratio, peak torque and work per repetition were the three forms of strength used to correlate against the flexibility scores.  Peak torque to body weight ration revealed a ­0.00 correlation for both the right and left legs.  Work done per repetition showed a ­0.00 correlation as well.  Peak toque scores when correlated against flexibility displayed a ­0.00 score for both the right and left leg.  All scores acquired are far below any significance level set at P < 0.05.  This study demonstrated that a correlation between peak torque, work done per repetition and peak torque to body weight ratio of Division 1 female athletes does  not play a role on flexibility or vice versa.

Key words:  flexibility, strength, correlation, peak torque, work done repetition, peak torque to body weight ratio

The perception of exertion is a simple ìmeasureî of exercise intensity.  According to Borg (1985), it is now used as a complement to physiological measurements, such as the heart rate.  The rating of perceived exertion by an individual, functions as an important indicator or ìmeasureî of physical strain.

The purpose of this study is to determine if a personís physical strain is perceived as higher than when that individual works out with somebody else.  This study will determine if there is a difference in exertion while working out alone or with someone.

The measurements taken during the study were the subjectís heart rate and the subjectís rating of perceived exertion throughout the twenty-minute exercise.

The data was analyzed by using dependent t-tests comparing the average RPE values of the group of RPE values taken while the subjects were bicycling alone, compared to the RPE values taken while the subjects were exercising with another subject.  There was no noted significant differences between the two trials with a P value for the heart rate was 0.63, and the P value for RPE was 0.73.  The mean heart rate while working out with a partner 132.13 with a standard deviation of (+/-) 2.17 and a RPE of 10.78 with a standard deviation of (+/-) 0.52.  The mean heart rate of the subjects exercising with a partner was 131.3 with a standard deviation of (+/-) 6.88, and a mean RPE of 10.92 (+/-) 0.53.

The use of sodium phosphate (NaPO4) supplementation to improve endurance performance has long been proposed without substantial evidence.  There are several investigations of NaPO4 supplementation in the literature, however the findings are equivocal.  Phosphate loading has been proposed to alter metabolic and cardiovascular functions including; an attenuated lactate threshold, an increased availability of inorganic phosphate for creatine phosphate synthesis, enhanced myocardial and cardiovascular efficiency, and an improved aerobic capacity.  To test the theory that NaPO4 could improve aerobic performance the current study was undertaken.  12 previously trained male subjects (Mean VO2max 60.6 ± 4.4 ml?kg-1?min-1) participated in a double blind crossover experiment to determine the effects of a commercial sodium phosphate supplement on maximal oxygen consumption (VO2max) and blood lactate.  Subjects performed an incremental VO2max test on a cycle ergometer using 3-minute stages. Lactate concentrations were determined from fingerstick blood samples at the end of each stage and immediately analyzed as whole blood.  After the completion of pre-supplement testing, subjects were randomly assigned either a sodium phosphate or a placebo supplement.  The supplementation regimen consisted of 1000mg of either dibasic sodium phosphate or placebo four times a day for 4 days.  On day 5 subjects returned to the lab to repeat the testing protocol.  Repeated measures analysis of variance (P< 0.05) indicated no significant effects of sodium phosphate supplementation in contrast to the placebo treatment for VO2max or blood lactate.  In conclusion, our data suggest that NaPO4 is an ineffective supplement when used to enhance endurance performance.