Current Research and Statistical Practices in Sport Science and a Need for Change

Current research ideologies in sport science allow for the possibility of investigators producing statistically significant results to help fit the outcome into a predetermined theory. Additionally, under the current Neyman-Pearson statistical structure, some argue that null hypothesis significant testing (NHST) under the frequentist approach is flawed, regardless. For example, a p-value is unable to measure the probability that the studied hypothesis is true, unable to measure the size of an effect or the importance of a result, and unable to provide a good measure of evidence regarding a model or hypothesis. Many of these downfalls are key questions researchers strive to answer following an investigation. Therefore, a shift towards a magnitude-based inference model, and eventually a fully Bayesian framework, is thought to be a better fit from a statistical standpoint and may be an improved way to address biases within the literature. The goal of this article is to shed light on the current research and statistical shortcomings the field of sport science faces today, and offer potential solutions to help guide future research practices

Application of Principal Components Analysis in Kinetics Study for Isometric Squat

Abstract available in the 10th Annual Coaches and Sport Science College

Identifying a Test to Monitor Weightlifting Performance in Competitive Male and Female Weightlifters

Monitoring tests are commonly used to assess weightlifter’s preparedness for competition. Although various monitoring tests have been used, it is not clear which test is the strongest indicator of weightlifting performance. Therefore, the purpose of this study was to (1) determine the relationships between vertical jump, isometric mid-thigh pull (IMTP) and weightlifting performance; and (2) compare vertical jumps to IMTP as monitoring tests of weightlifting performance in a large cohort of male and female weightlifters. Methods: Fifty-two competitive weightlifters (31 males, 21 females) participated in squat and countermovement jump testing (SJ, CMJ), and IMTP testing performed on force plates. All laboratory testing data was correlated to a recent competition where the athletes had attempted to peak. Results: Squat jump height (SJH) was the strongest correlate for men and women with the Sinclair Total (r = 0.686, p ≤ 0.01; r = 0.487, p ≤ 0.05, respectively) compared to countermovement jump height (r = 0.642, p ≤ 0.01; r = 0.413, p = 0.063), IMTP peak force allometrically scaled to body mass (r = 0.542, p ≤ 0.01; r = −0.044, p = 0.851) and rate of force development at 200 ms (r = 0.066, p = 0.723; r = 0.086, p = 0.711), respectively. Further, SJH was a stronger correlate of relative weightlifting performance compared to IMTP peak force in females (p = 0.042), but not male weightlifters (p = 0.191). Conclusions: Although CMJ and IMTP are still considered strong indicators of weightlifting performance, SJH appears to be the most indicative measure of weightlifting performance across a wide-range of performance levels. Thus, SJH can be used as a reliable measure to monitor weightlifting performance in male and female weightlifters

Using the Minimax Accelerometer to Quantify the Demands of Preseason Training in NCAA Volleyball: A Descriptive Case-Study Study

Abstract available in the 9th Annual Coaches and Sport Science College

The Efficacy of Partial Squats on Measures of Strength and Explosiveness: An Exploratory Study

Abstract available in the 8th Annual Coaches and Sport Science College

Increases in Variation of Barbell Kinematics Are Observed with Increasing Intensity in a Graded Back Squat Test

The purpose of the current study was two-fold: (1) To examine the variation in velocity and power with increasing intensity in the back squat among subjects; and (2) To explore individual subject characteristics as possible explanations for variations of velocity in the back squat. Fourteen recreationally trained male subjects with experience in the back squat agreed to participate in the study (age = 25.0 ± 2.6 years, height = 178.9 ± 8.1 cm, body mass = 88.2 ± 15.8 kg). One-repetition maximums (1RM) were performed for each subject on force platforms with four linear position transducers attached to the barbell. The 1RM assessment was immediately preceded by warm-up sets at 65%, 75%, 85%, and 95% of estimated 1RM for 5, 3, 2, and 1 repetitions, respectively. Mean concentric velocity (MCV) and mean power were recorded for each intensity condition and were analyzed using Pearson correlation to determine the relationship between each variable and relative intensity (%1RM). Statistically significant negative relationships existed between %1RM and MCV (r = −0.892) and mean power (r = −0.604). Between-subject coefficient of variation tended to increase as %1RM increased for both MCV and mean power. These results suggest that MCV is superior to mean power as an indicator of relative intensity in the back squat. Additionally, the between-subject variation observed at higher intensities for MCV and mean power support the use of velocity ranges by strength and conditioning coaches

The Effects of Strength Training on Isometric Force Production Symmetry in Recreationally Trained Males

Objectives: The purpose of this investigation was to determine what effect a bilateral strength training regimen has on isometric force production symmetry and if changes in force production symmetry can be accounted for by differences in pre-intervention strength levels. Design: Sixteen recreationally trained males (1-RM squat: 146.8 ± 23.0 kg.) were assigned to two groups for the 7-week training intervention: strong (S) and weak (W) based on pre-training squat isometric peak force allometrically scaled (IPFa) at 120° knee angle. Methods: Subjects completed a 7-week training intervention following a block-periodized model and were tested on measures of dynamic (1RM squat) and isometric (isometric squat at 90° and 120° knee angle) strength pre- and post-intervention. The degree of bilateral lower limb asymmetry was calculated as a percentage where 0% symmetry index (SI) indicates perfect symmetry on the isometric squat.Results: ANCOVA results showed no statistical difference between groups for all dependent variables when pre-intervention IPFa 120° scores were used as the covariate. Paired t-tests results showed both groups statistically improved 1RM squat and IPFa 120° (p \u3c 0.05). IPFa 120° SI decreased statistically from pre-training in the W group (p = 0.03). Independent t-test results showed the W group had statistically larger pre-intervention SI scores for IPFa 90° (p = 0.045) and IPFa 120° (p = 0.007); however this difference was no longer present following strength training. There was a strong inverse relationship between pooled IPFa 120° and IPFa 120° SI (r = -0.64, p = 0.004). Conclusions: The findings of the current study support the notion that weaker individuals can augment lower limb symmetry with strength training. The same does not seem to be true for stronger individuals who already have a low symmetry index score. These findings indicate that strength training improves force production symmetry in relatively weak males, which may be important for bilateral tasks and injury potential reduction

Validity of the Short Recovery and Stress Scale in Collegiate Weightlifters

Introduction: Monitoring an athlete’s stress and recovery state across sequential training bouts can be used to gauge fitness and fatigue levels (i.e., preparedness). Previous studies have used jumping performance, biochemical markers, and questionnaires to estimate preparedness. However, self-report questionnaires are the most common due to economical and practical means. The Short Recovery and Stress Scale (SRSS) is an 8-item questionnaire ideal for monitoring; however, convergent validity of the SRSS with physiological and performance measures needs to be investigated. Purpose: Thus, the purpose of this study was to determine whether changes in collegiate weightlifter’s training volume-load, biochemical markers, and jumping performance correlate to changes in the SRSS. Methods: 12 collegiate weightlifters (8 males, 4 females) with \u3e1yr of competition experience trained for 4 weeks and were tested at the beginning of each week (T1-T4). Training volume-load with displacement (VLd) was monitored weekly for all exercises. Testing was conducted following an overnight fast and included hydration, SRSS (0-6 scale with 6 indicating highest recovery and stress), and blood draws (resting testosterone (T), cortisol (C), T:C, creatine kinase (CK)) followed by unloaded (0kg) and loaded (20kg) squat jumps (SJ) on force platforms. Pearson correlation coefficients were calculated between the change in SRSS scores and all other variables from T1-T2, T1-T3, and T1-T4. Alpha level was set at p\u3c 0.05. Results: Inverse relationships were observed between changes in recovery items and C (r= -0.61 to -0.72, p\u3c 0.05), and unloaded and loaded SJ height and relative peak power (r= -0.59 to -0.64, p\u3c 0.05) from T1 to T2, and T1 to T3. Similarly, positive relationships were observed between changes in stress items and C (r=0.61 to 0.72, p\u3c 0.05), and unloaded and loaded SJ height and relative peak power (r=0.58 to 0.84, p\u3c 0.05) across all time points. No significant relationships were observed between changes in SRSS items and VLd or T, T:C, CK. Conclusion: Relationships between changes in some SRSS items and C agree with previous findings highlighting C as an indicator of training stress. Nonetheless, the non-significant relationships between changes in SRSS items, VLd, and other biochemical markers disagrees with previous findings. This may partly be explained by the smaller undulations in VLd in the current study, which is characteristic of actual training. Further, relationships between changes in some SRSS items and jumping performance were opposite of what was expected indicating athlete’s perception of their stress and recovery state does not always correspond with their ability to perform. Practical Application: These results provide some evidence for the convergent validity of the SRSS. Nonetheless, weightlifting coaches should be cautious in using results from a single test to estimate an athlete’s preparedness. Thus, we recommend the SRSS be included as part of a multi-dimensional monitoring program for weightlifters

The Relationship of Force Production Asymmetry and Performance in Athletes of Different Strength Levels

The purpose of this study was to evaluate the relationship between force production asymmetry and performance of athletes with differing strength levels in males and females. Collegiate athletes (n=129) from various sports were ranked according to isometric mid-thigh pull peak force and the top (‘strong’) and bottom (‘weak’) 25% were used for analysis. Symmetry index (SI) scores were calculated and correlated with their respective force-time characteristics using bivariate correlations. For the weaker males, several negative moderate correlations were observed; however, no statistically significant correlations were observed for the females in either group. These findings indicate that force production asymmetry is inversely related to performance in weaker male athletes during isometric strength testing; however, similar to previous findings, this relationship is not apparent in stronger males