Methodological and statistical considerations for exercise-related hormone evaluations

Improvements in laboratory techniques have allowed research related to exercise endocrinology to flourish. The emerging literature, however, is often inconsistent and contradictory. The discrepancies in research findings are possibly the result of poor control of confounding variables and/or inappropriate methodologies or analyses. Environmental and pretesting behavioural conditions must be standardised to minimise the influence of variables not directly related to the investigation. Environmental temperature and relative humidity, alcohol, caffeine and nicotine intake, prandial state, sleep deprivation and previous exercise can each alter hormonal responses to exercise. Both prescription and over-the-counter medications can also modify normal hormonal secretions thereby confusing exercise-induced findings. Specimen collection and analysis procedures must be controlled carefully. Changes in plasma volume related to postural changes or tourniquet-induced stasis can confound attempts to isolate exercise-related endocrine responses. The established circadian and rhythmical variations characteristic of many hormones need to be controlled. The specimen selection (plasma, serum, urine, etc), collection, storage and analysis procedures should be carefully planned and evaluated. The magnitude of haemolysis, analytical and biological variation must also be monitored. Isolating the hormonal perturbations resulting from a particular exercise variable can be very difficult. Exercise intensity, duration, mode, frequency and volume may each have specific effects on the endocrine changes seen with exercise and training. Furthermore, hormonal responses to exercise are dependent upon initial training status and fitness level. The statistical procedures and data presentation options selected to convey experimental findings can bias experimental results. The descriptive and inferential statistics to be used for data analysis should be preplanned and consistent with the underlying assumptions of the analytical procedure. Careful consideration should be given to the biological relevance of statistically significant findings. In some cases, data transformations (e.g. absolute vs relative changes, logarithmic) should be considered for analysis or presentation. Given the individual nature of hormonal responses to exercise, emphasis should be placed presenting individual data. Other considerations, including age, sex, racial origin and disease conditions need to be controlled for when trying to examine exercise-induced hormone changes.

Modifications to hydra-gym equipment provide for clinically useful strength measurements

Modifications were made to the Series III-311 Omnikinetic Hydra-Gym apparatus (Hydra-Fitness Industries Inc., Belton, TX) in an effort to provide relatively inexpensive yet clinically useful isokinetic strength measurements. Signal transmission and processing functions were installed to calculate relevant strength characteristics for knee extension/flexion motions. Results from the modified Hydra-Gym were compared with matched procedures on the Kin-Com (model 500-10, Chattecx Corporation, Chattanooga, TN). Subjects (N = 10) performed three maximal concentric right knee extension/flexion cycles at different resistance settings (2, 4, and 6) on the Hydra-Gym and the corresponding angular velocities on the Kin-Com (190, 125, and 40 degrees/sec, respectively). Each subject completed eight testing sessions, four on each dynamometer. A five-way analysis of variance on the peak torque data revealed no significant difference between dynamometers; however, there was a significant interaction between dynamometer and extension/flexion measurements. The variance in angle of peak torque data was significantly different between dynamometers, with Hydra-Gym showing superior reproducibility (p < 0.005). Mechanical differences between dynamometers produced slightly different, though comparable and consistent, measurement values. Care must be taken when evaluating hamstring/quadriceps ratios from the Hydra-Gym because the interaction noticed between dynamometer and extension/flexion may exaggerate muscle imbalances. In summary, modifications to the Hydra-Gym appear to provide clinicians with a reliable and clinically useful strength testing alternative.

Ergogenic effects of phosphate loading: physiological fact or methodological fiction?

Inorganic phosphate (Pi) supplementation has been reported to provide ergogenic benefits, though the research findings are inconsistent. Several confounding influences may explain these results, including mode of exercise, exercise intensity, dietary intake, daily biological fluctuations, type of supplement, administered dose of the supplement, washout period, length of loading period, fitness level of subjects, blood volume alterations, and sample collection and analysis techniques. This review provides a critical analysis of the methodological difficulties that may contribute to the equivocal research findings pertaining to Pi supplementation.

Anabolic steroids in sport

The use of androgenic-anabolic steroids (AAS) for enhancing athletic performance and body image is widespread. An increasing number of elite and recreational athletes of varying ages and athletic pursuits are using AAS. Sophisticated patterns of AAS use are supported by unethical and illegal distribution channels. Various testosterone-derived preparations attempt to manipulate pharmacological characteristics in an effort to maximize anabolic potential while minimizing androgenic effects. Although anecdotal and theoretical information suggests that AAS have positive ergogenic properties, the experimental evidence is equivocal. In addition to the ethical and legal implications of using AAS, there are diverse, though often reversible, medical and behaviour ramifications. In an effort to control and discourage AAS use, relevant sport governing bodies have implemented various testing and educational programs with undetermined success.