Chronic Training Load Research Articles

Dissociated Time Course of Recovery Between Strength and Power After Isoinertial Resistance Loading in Rugby Union Players.

Kennedy, RA and Drake, D. Dissociated time course of recovery between strength and power after isoinertial resistance loading in rugby union players. J Strength Cond Res 32(3): 748-755, 2018-There is a substantial amount of research on the responses to isometric and eccentric loading. However, only a paucity of literature exists on the responses to isoinertial loading, especially in trained athletic populations using realistic loading protocols. The purpose of this study was to examine the acute neuromuscular response to a bout of isoinertial resistance loading in elite rugby players. Seventeen male (age: 19.5 ± 2.3 years) rugby union players performed a conventional maximal isoinertial resistance loading protocol. Countermovement jump (CMJ) and maximal voluntary isometric contraction (MVC) squat performance were measured on 3 occasions: at baseline, immediately post, and 48 hour post. The results indicated that the decrease in MVC (9.7%) is greater than or comparable with the CMJ output variables (4.2-10.3%), immediately postexercise. Although isometric strength had demonstrated a full recovery at 48 hour post, many of the key CMJ output variables were still impaired (p ≤ 0.05). Similar findings were observed in the normalized CMJ curves. Complete recovery of the ability to rapidly produced force may require more than 48 hours in many athletes. Individual responses should, therefore, be monitored to help plan acute and chronic training loads. It is recommended that future fatigue studies should incorporate temporal phase analyses to consider the power-, force-, velocity-, and displacement-time curves.

Physical Preparation Factors That Influence Technical and Physical Match Performance in Professional Australian Football.

To examine the collective influence of a range of physical preparation elements on selected performance measures during Australian football match play. Prospective and longitudinal. Data were collected from 34 professional Australian football players from the same club during the 2016 Australian Football League competition season. Match activity profiles and acute (7-d) and chronic (3-wk) training loads were collected using global positioning system devices. Training response was measured by well-being questionnaires completed prior to the main training session each week. Maximal aerobic running speed (MAS) was estimated by a 2-km time trial conducted during preseason. Coach ratings were collected from the senior coach and 4 assistants after each match on a 5-point Likert scale. Player ratings were obtained from a commercial statistics provider. Fifteen matches were analyzed. Linear mixed models were constructed to examine the collective influence of training-related factors on 4 performance measures. Muscle soreness had a small positive effect (ES: 0.12) on Champion Data rating points. Three-week average high-speed running distance had a small negative effect (ES: 0.14) on coach ratings. MAS had large to moderate positive effects (ES: 0.55 to 0.47) on relative total and high-speed running distances. Acute total and chronic average total running distance had small positive (ES: 0.13) and negative (ES: 0.14) effects on relative total and high-speed running distance performed during matches, respectively. MAS should be developed to enhance players' running performance during competition. Monitoring of physical preparation data may assist in reducing injury and illness and increasing player availability but not enhance football performance.

Monitoring loads and non-contact injury during the transition from club to National team prior to an international football tournament: A case study of the 2014 FIFA World Cup and 2015 Asia Cup

ObjectivesInjured and non-injured national team footballers were compared for external and internal loads during transition from club to National team training camp. DesignProspective Case Study. MethodsLoad and injury data were collected from the same National team prior to and during training camps of 2 tournaments; World (n=17) and Asian Cups (n=16). External (number sessions) and internal (s-RPE) loads were collected 4-weeks prior to and during camps. The acute:chronic load ratio was calculated for the first week of camp based on the mean of previous 4-weeks. Respective loads and ratios were compared between injured and non-injured players for non-contact injuries occurring during camp. ResultsSeven non-contact injuries occurred during World Cup camp and 1 during Asian Cup (preventing statistical analyses). Small-to-moderate effect sizes were found for lower chronic internal loads (ES=0.57; 90% CI: 0.39–1.08) and higher acute:chronic ratio (ES=0.45; 90% CI: 0.31–0.87) for injured compared to non-injured players. Moderate-large effects (ES=0.83; 90% CI: 0.56–1.60) were evident for increased acute:chronic ratio for number of sessions in injured compared to non-injured players. However, small-moderate effect sizes were present for lower chronic training and match loads (ES=0.55; 90% CI: 0.38–1.06) in injured players prior to the World Cup camp, alongside an increased number of sessions in week 1 of camp (ES=0.47; 90% CI: 0.33–0.91). ConclusionsPlayers incurring non-contact injury during training camp prior to an international tournament performed less prior chronic external and internal load and a concomitant higher relative increase in camp, thus representing a practical marker to monitor in national teams.

High-speed running and sprinting as an injury risk factor in soccer: Can well-developed physical qualities reduce the risk?

ObjectivesThis study investigated the association between high-speed running (HSR) and sprint running (SR) and injuries within elite soccer players. The impact of intermittent aerobic fitness as measured by the end speed of the 30–15 intermittent fitness test (30–15VIFT) and high chronic workloads (average 21-day) as potential mediators of injury risk were also investigated. DesignObservational Cohort Study. Methods37 elite soccer players from one elite squad were involved in a one-season study. Training and game workloads (session-RPE×duration) were recorded in conjunction with external training loads (using global positioning system technology) to measure the HSR (>14.4kmh−1) and SR (>19.8kmh−1) distance covered across weekly periods during the season. Lower limb injuries were also recorded. Training load and GPS data were modelled against injury data using logistic regression. Odds ratios (OR) were calculated with 90% confidence intervals based on 21-day chronic training load status (sRPE), aerobic fitness, HSR and SR distance with these reported against a reference group. ResultsPlayers who completed moderate HSR (701–750-m: OR: 0.12, 90%CI: 0.08–0.94) and SR distances (201–350-m: OR: 0.54, 90%CI: 0.41–0.85) were at reduced injury risk compared to low HSR (≤674-m) and SR (≤165-m) reference groups. Injury risk was higher for players who experienced large weekly changes in HSR (351–455-m; OR: 3.02; 90%CI: 2.03–5.18) and SR distances (between 75–105-m; OR: 6.12, 90%CI: 4.66–8.29). Players who exerted higher chronic training loads (≥2584 AU) were at significantly reduced risk of injury when they covered 1-weekly HSR distances of 701–750m compared to the reference group of <674m (OR=0.65, 90% CI 0.27–0.89). When intermittent aerobic fitness was considered based on 30–15VIFT performance, players with poor aerobic fitness had a greater risk of injury than players with better-developed aerobic fitness. ConclusionsExposing players to large and rapid increases in HSR and SR distances increased the odds of injury. However, higher chronic training loads (≥2584 AU) and better intermittent aerobic fitness off-set lower limb injury risk associated with these running distances in elite soccer players.

Optimizing Preseason Training Loads in Australian Football.

To investigate whether preseason training plans for Australian football can be computer generated using current training-load guidelines to optimize injury-risk reduction and performance improvement. A constrained optimization problem was defined for daily total and sprint distance, using the preseason schedule of an elite Australian football team as a template. Maximizing total training volume and maximizing Banister-model-projected performance were bothconsidered optimization objectives. Cumulative workload and acute:chronic workload-ratio constraints were placed on training programs to reflect current guidelines on relative and absolute training loads for injury-risk reduction. Optimization software was then used to generate preseason training plans. The optimization framework was able to generate training plans that satisfied relative and absolute workload constraints. Increasing the off-season chronic training loads enabled the optimization algorithm to prescribe higher amounts of "safe" training and attain higher projected performance levels. Simulations showed that using a Banister-model objective led to plans that included a taper in training load prior to competition to minimize fatigue and maximize projected performance. In contrast, when the objective was to maximize total training volume, more frequent training was prescribed to accumulate as much load as possible. Feasible training plans that maximize projected performance and satisfy injury-risk constraints can be automatically generated by an optimization problem for Australian football. The optimization methods allow for individualized training-plan design and the ability to adapt to changing training objectives and different training-load metrics.

Chronic Training Load, But Not Stress Or Sleep, Is An Independent Predictor Of Illness In Female Youth Athletes

Chronic Training Load, But Not Stress Or Sleep, Is An Independent Predictor Of Illness In Female Youth Athletes

NOVEL RISK FACTORS ASSOCIATED WITH MORE SEVERE EXERCISE ASSOCIATED MUSCLE CRAMPING (EAMC): A PROSPECTIVE COHORT STUDY OF 41 698 DISTANCE RUNNERS

BackgroundEAMC is a common clinical syndrome in endurance runners, and can range in severity. Risk factors for EAMC have been identified and include age, gender, racing distance, a history of...

NOVEL DIRECT AND INDIRECT EFFECTS OF RISK FACTORS FOR EXERCISE ASSOCIATED MUSCLE CRAMPING (EAMC) IN A COHORT OF 41 698 DISTANCE RUNNERS

BackgroundWe recently identified novel risk factors for EAMC in distance runners, including age, gender, racing distance, a history of chronic diseases, medication, training and competition load, and running injuries. The...

Two Training-Load Paradoxes: Can We Work Harder and Smarter, Can Physical Preparation and Medical Be Teammates?

The authors have observed that in professional sporting organizations the staff responsible for physical preparation and medical care typically practice in relative isolation and display tension as regards their attitudes toward training-load prescription (much more and much less training, respectively). Recent evidence shows that relatively high chronic training loads, when they are appropriately reached, are associated with reduced injury risk and better performance. Understanding this link between performance and training loads removes this tension but requires a better understanding of the relationship between the acute:chronic workload ratio (ACWR) and its association with performance and injury. However, there remain many questions in the area of ACWR, and we are likely at an early stage of our understanding of these parameters and their interrelationships. This opinion paper explores these themes and makes recommendations for improving performance through better synergies in support-staff approaches. Furthermore, aspects of the ACWR that remain to be clarified-the role of shared decision making, risk:benefit estimation, and clearer accountability-are discussed.

High chronic training loads and exposure to bouts of maximal velocity running reduce injury risk in elite Gaelic football.

To examine the relationship between chronic training loads, number of exposures to maximal velocity, the distance covered at maximal velocity, percentage of maximal velocity in training and match-play and subsequent injury risk in elite Gaelic footballers. Prospective cohort design. Thirty-seven elite Gaelic footballers from one elite squad were involved in a one-season study. Training and game loads (session-RPE multiplied by duration in min) were recorded in conjunction with external match and training loads (using global positioning system technology) to measure the distance covered at maximal velocity, relative maximal velocity and the number of player exposures to maximal velocity across weekly periods during the season. Lower limb injuries were also recorded. Training load and GPS data were modelled against injury data using logistic regression. Odds ratios (OR) were calculated based on chronic training load status, relative maximal velocity and number of exposures to maximal velocity with these reported against the lowest reference group for these variables. Players who produced over 95% maximal velocity on at least one occasion within training environments had lower risk of injury compared to the reference group of 85% maximal velocity on at least one occasion (OR: 0.12, p=0.001). Higher chronic training loads (≥4750AU) allowed players to tolerate increased distances (between 90 to 120m) and exposures to maximal velocity (between 10 to 15 exposures), with these exposures having a protective effect compared to lower exposures (OR: 0.22 p=0.026) and distance (OR=0.23, p=0.055). Players who had higher chronic training loads (≥4750AU) tolerated increased distances and exposures to maximal velocity when compared to players exposed to low chronic training loads (≤4750AU). Under- and over-exposure of players to maximal velocity events (represented by a U-shaped curve) increased the risk of injury.

Monitoring the athlete training response: subjective self-reported measures trump commonly used objective measures: a systematic review

BackgroundMonitoring athlete well-being is essential to guide training and to detect any progression towards negative health outcomes and associated poor performance. Objective (performance, physiological, biochemical) and subjective measures are all...

Commentaries on Viewpoint: Can muscle size fully account for strength differences between children and adults?

# {#article-title-2} to the editor: As comprehensively explained in their Viewpoint article ([1][1]), the answer to the question posed in the title has received conflicting answers. Since the contractile machinery in children is the same as that in adults, there is no reason to believe that

Seasonal variation of haemoglobin mass in internationally competitive female road cyclists

In order to quantify the seasonal variability of haemoglobin mass (Hb(mass)) in cyclists during a competitive season, and investigate whether variability is associated with changes in training load or performance, Hb(mass) was measured in 10 internationally competitive female road cyclists approximately once per month for 2-10 months via CO-rebreathing. Power meters were used to quantify daily load (Training Stress Scores) during training and racing, from which cumulative training load units for 7, 14, 28 and 42 day were calculated. Maximal mean power (MMP) for 1, 4, 10 and 25 min, performed during training or racing was used as a surrogate for performance. The relationship between changes in training load (%DeltaTraining) and changes in Hb(mass) (%DeltaHb(mass)), and between %DeltaHb(mass) and changes in MMP (%DeltaMMP) was established via regression analysis. Individual coefficients of variation (CV) in Hb(mass) ranged from 2.0 to 4.4%. The weighted mean CV in Hb(mass) was 3.3% (90% Confidence Limits: 2.9-3.8%) or 23 g over the average 6.6 +/- 2.3 month monitoring period. The effect of %DeltaTraining on %DeltaHb(mass) was small for 7 and 14 day (r = 0.22 and 0.29), moderate for 42 day (r = 0.35) and large for 28 day (r = 0.56). The regression slope was greatest for 42 day, with a 10% change in training associated with a approximately 1% change in Hb(mass). The relationship between %DeltaHb(mass) and %DeltaMMP was approximately 0.5:1 for MMP(1min),(10 min) and (25 min) and approximately 1:1 for MMP(4 min), respectively. Hb(mass) varies by approximately 3% in female cyclists during a competitive season. Some of the variation may be related to oscillations in chronic training load.

Performance Modeling in an Olympic 1500-m Finalist: A Practical Approach

The purpose of this study was to test if a simplified impulse-response (IR) model would correlate with competition performances in an elite middle-distance runner over a period of 7 years that encompassed two Olympiads. Daily recorded pace and time obtained from training logs of this individual for the years 2000 to 2006 were used to calculate the impulse (training stress score, or TSS). The daily TSS was used to generate acute and chronic training loads (ATL and CTL, respectively), and a model response output, or p(t), was calculated based on the relationship p(t) = CTL - ATL. Competition performances (800 m-1 mile) were converted to Mercier scores (MS) and compared to p(t) and model parameters TSS, ATL, and CTL. MS was positively correlated with model output response p(t) (p < 0.01) and negatively with ATL (p < 0.01). Quadratic relationships were also observed between MS and both p(t) and CTL (p < 0.001), potentially indicating an optimal balance between fitness, fatigue, and performance. The results of this study demonstrate that the output of this simplified IR modeling approach correlates with performance in at least 1 elite athlete. Further studies are necessary to determine the generalizability of this method, but coaches may wish to use this approach to analyze previous training and performance relationships and iteratively modify training to optimize performance.