Replacing statistical significance and non-significance with better approaches to sampling uncertainty.

A sample provides only an approximate estimate of the magnitude of an effect, owing to sampling uncertainty. The following methods address the issue of sampling uncertainty when researchers make a claim about effect magnitude: informal assessment of the range of magnitudes represented by the confidence interval; testing of hypotheses of substantial (meaningful) and non-substantial magnitudes; assessment of the probabilities of substantial and trivial (inconsequential) magnitudes with Bayesian methods based on non-informative or informative priors; and testing of the nil or zero hypothesis. Assessment of the confidence interval, testing of substantial and non-substantial hypotheses, and assessment of Bayesian probabilities with a non-informative prior are subject to differing interpretations but are all effectively equivalent and can reasonably define and provide necessary and sufficient evidence for substantial and trivial effects. Informative priors in Bayesian assessments are problematic, because they are hard to quantify and can bias the outcome. Rejection of the nil hypothesis (presented as statistical significance), and failure to reject the nil hypothesis (presented as statistical non-significance), provide neither necessary nor sufficient evidence for substantial and trivial effects. To properly account for sampling uncertainty in effect magnitudes, researchers should therefore replace rather than supplement the nil-hypothesis test with one or more of the other three equivalent methods. Surprisal values, second-generation p values, and the hypothesis comparisons of evidential statistics are three other recent approaches to sampling uncertainty that are not recommended. Important issues beyond sampling uncertainty include representativeness of sampling, accuracy of the statistical model, individual differences, individual responses, and rewards of benefit and costs of harm of clinically or practically important interventions and side effects.

La punción seca aumenta el rendimiento de salto en jugadores élite de vóley playa / Deep Dry Needling Enhances Jump Performance in Elite Beach Volleyball Players

El objetivo del presente estudio es evaluar si la aplicación de la punción seca en los puntos gatillo miofasciales latentes se asocia con cambios en el rendimiento de salto. Seis jugadores internacionales de vóley playa sub-21 recibieron tratamiento en el vasto lateral y medial. Se midió la altura de salto SJ y CMJ en cuatro sesiones: antes y después de la intervención (efecto agudo), 48 h y 7 días tras la intervención (efectos a largo plazo). Los jugadores mostraron una pequeña disminución post-intervención seguida de un aumento no significativo a las 48 h. Sin embargo, ambos tipos de salto dieron lugar a un aumento con efecto moderado muy probable tras una semana: 4,13 cm (+10,8%) y 3,54 cm (+8,9%) para SJ y CMJ, respectivamente. A pesar de este aumento significativo, la disminución del rendimiento post-test desalienta su uso inmediatamente antes de una competición. (AU)

The present study aims to assess whether Deep Dry Needling in latent Myofascial Trigger Points is associated with changes in jumping performance. Six Under-21 international beach volleyball players received intervention in vastus lateralis and medialis of the quadriceps. Three squat jump (SJ) and countermovement jump (CMJ) heights were measured in four sessions: pre- and post-intervention (acute effect), 48 h and 7 days after intervention (long-term effects). The players showed a small decrease after the intervention followed by a non-significant increase at 48 h. However, both jump types resulted in very likely moderate increase after one week of intervention: 4.13 cm (+10.8%) and 3.54 cm (+8.9%) for SJ and CMJ, respectively (3 times the smallest worthwhile change). Despite this significant increase, the decreased performance in post-test results discourages practitioners from using this technique just before a competition. (AU)

Factors Affecting Cyclists' Chances of Success in Match-Sprint Tournaments.

PURPOSE: To further the understanding of elite athlete performance in complex race environments by examining the changes in cyclists' performance between solo time trials and head-to-head racing in match-sprint tournaments. METHODS: Analyses were derived from official results of cyclists in 61 elite international sprint tournaments (2000-2016), incorporating the results of 2060 male and 1969 female head-to-head match races. Linear mixed modeling of log-transformed qualification and finish ranks was used to determine estimates of performance predictability as intraclass correlation coefficients. Correlations between qualifying performance and final tournament rank were also calculated. Chances of winning head-to-head races were estimated adjusting for the difference in the cyclists' qualifying times. All effects were evaluated using magnitude-based inference. RESULTS: Minor differences in predictability between qualification time trial and final tournament rank were suggestive of more competitiveness among men in the overall tournament. Performance in the qualification time trial was strongly correlated with, but not fully indicative of, performance in the overall tournament. Correspondingly, being the faster qualifier had a large positive effect on the chances of winning a head-to-head race, but small substantial differences between riders remained after adjustment for time-trial differentials. CONCLUSIONS: The present study provides further insight into how real-world competition data can be used to investigate elite athlete performance in sports where athletes must directly interact with their opponents. For elite match-sprint cyclists, qualifying time-trial performance largely determines success in the overall tournament, but there is evidence of a consistent match-race ability that modifies the chances of winning head-to-head races.

Physiological Characteristics of Projected Starters and Non-Starters in the Field Positions from a Division I Women's Soccer Team.

NCAA soccer features different substitution rules compared to FIFA-sanctioned matches, with a greater availability of players who can enter the game. This could influence the physiological characteristics of the field position starters (ST) and non-starters (NST) within a collegiate women's team, which has not been previously analyzed. Thus, 22 field players from the same Division I women's soccer squad completed: vertical and standing broad jumps; 30-meter (m) sprint (0-5, 0-10, 0-30 m intervals); pro-agility and 60-yard shuttle; and the Yo-Yo Intermittent Recovery Test Level 1. Players were defined into ST (n=10) and NST (n=12) by the coaching staff. A one-way ANOVA derived any significant (p≤0.05) between-group differences, and effect sizes were used for a magnitude-based inference analysis. Z-scores were also calculated to document worthwhile differences above or below the squad mean for the groups. The results showed no significant between-group differences for any of the performance tests. ST did have a worthwhile difference above the squad mean in the 0-10 and 0-30 m sprint intervals, while NST had a worthwhile difference below the squad mean in the 0-30 m interval. Physiological characteristics between ST and NST from the analyzed Division I squad were similar, although ST were generally faster. The similarities between ST and NST may be a function of the team's training, in that all players may complete the same workouts. Nonetheless, if all players exhibit similar physiological capacities, with appropriate substitutions by the coach a collegiate team should be able to maintain a high work-rate throughout a match.

Training-induced changes in physical performance can be achieved without body mass reduction after eight week of strength and injury prevention oriented programme in volleyball female players.

The purpose of the study was to analyse the changes in muscle strength, power, and somatic parameters in elite volleyball players after a specific pre-season training programme aimed at improving jumping and strength performance and injury prevention. Twelve junior female volleyball players participated in an 8-week training programme. Anthropometric characteristics, isokinetic peak torque (PT) single-joint knee flexion (H) and extension (Q) at 60º/s and 180º/s, counter movement jump (CMJ), squat jump (SJ), and reactive strength index (RSI) were measured before and after intervention. Significant moderate effects were found in flexor concentric PT at 60º/s and at 180 º/s in the dominant leg (DL) (18.3±15.1%, likely; 17.8±11.2%, very likely) and in extensor concentric PT at 180º/s (7.4%±7.8%, very likely) in the DL. In the non-dominant leg (NL) significant moderate effects were found in flexor concentric PT at 60º/s and at 180º/s (13.7±11.3%, likely; 13.4±8.0%, very likely) and in extensor concentric PT at 180º/s (10.7±11.5%, very likely). Small to moderate changes were observed for H/QCONV in the DL at 60º/s and 180º/s (15.9±14.1%; 9.6±10.4%, both likely) and in the NL at 60º/s (moderate change, 9.6±11.8%, likely), and small to moderate decreases were detected for H/QFUNC at 180º/s, in both the DL and NL (-7.0±8.3%, likely; -9.5±10.0%, likely). Training-induced changes in jumping performance were trivial (for RSI) to small (for CMJ and SJ). The applied pre-season training programme induced a number of positive changes in physical performance and risk of injury, despite a lack of changes in body mass and composition.

Foam rolling for delayed-onset muscle soreness and recovery of dynamic performance measures.

CONTEXT: After an intense bout of exercise, foam rolling is thought to alleviate muscle fatigue and soreness (ie, delayed-onset muscle soreness [DOMS]) and improve muscular performance. Potentially, foam rolling may be an effective therapeutic modality to reduce DOMS while enhancing the recovery of muscular performance. OBJECTIVE: To examine the effects of foam rolling as a recovery tool after an intense exercise protocol through assessment of pressure-pain threshold, sprint time, change-of-direction speed, power, and dynamic strength-endurance. DESIGN: Controlled laboratory study. SETTING: University laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 8 healthy, physically active males (age = 22.1 ± 2.5 years, height = 177.0 ± 7.5 cm, mass = 88.4 ± 11.4 kg) participated. INTERVENTION(S): Participants performed 2 conditions, separated by 4 weeks, involving 10 sets of 10 repetitions of back squats at 60% of their 1-repetition maximum, followed by either no foam rolling or 20 minutes of foam rolling immediately, 24, and 48 hours postexercise. MAIN OUTCOME MEASURE(S): Pressure-pain threshold, sprint speed (30-m sprint time), power (broad-jump distance), change-of-direction speed (T-test), and dynamic strength-endurance. RESULTS: Foam rolling substantially improved quadriceps muscle tenderness by a moderate to large amount in the days after fatigue (Cohen d range, 0.59 to 0.84). Substantial effects ranged from small to large in sprint time (Cohen d range, 0.68 to 0.77), power (Cohen d range, 0.48 to 0.87), and dynamic strength-endurance (Cohen d = 0.54). CONCLUSIONS: Foam rolling effectively reduced DOMS and associated decrements in most dynamic performance measures.