Acute Workloads Research Articles

Professional football training and recovery: A longitudinal study on the effects of weekly conditioning session and workload variables.

The main purpose of this longitudinal study was to investigate football players' recovery status, through hormonal response, in relation to accumulated workload at two comparable time points of the first (T1) and second half (T2) of the competitive season. Moreover, this study investigated athletes' hormonal response to a typical weekly conditioning session (5 days before match: MD-5), at T1 and T2, to detect changes in players' recovery capability over time. Salivary cortisol (sC) and testosterone (sT) of 24 professional players (27.8 ± 4.1 years of age) were collected before, after, and 24 hours following MD-5 in two comparable microcycles of T1 and T2. GPS training data (total and high-intensity distance) of the 7 and 28 days before sampling were used to obtain athletes' acute and chronic workloads. Results showed a pre-training significant decrease of sT and an increase of sC (p<0.05) in T2, compared to T1. Moreover, athletes showed high sC and low sT levels before, after and 24 hours following MD-5 in T2. Workload analysis revealed significant correlations of chronic load with sC (r = 0.45, p = 0.056) and T/C ratio (r = -0.59; p = 0.007). These results suggested that, in professional football, chronic workload has a greater impact on players' recovery time than acute workload over the sport season. Moreover, athletes' hormonal response to the weekly conditioning session at T2 revealed an altered anabolic/catabolic balance, highlighting the key role of continuous internal and external workload monitoring during the season.

Is Workload Associated With Oblique Injuries in Professional Baseball Players?

Oblique strains have become a common injury among professional baseball players. The influence of player workload on oblique strains remains unknown. To determine whether workload is a risk factor for oblique strains in professional baseball players. We hypothesized that fewer days of rest, more innings pitched/fielded per game, and more batters faced/plate appearances per game would significantly increase a player's risk of sustaining an oblique strain. Case-control study; Level of evidence, 3. All professional baseball players who sustained an oblique strain between 2011 and 2017 were identified using the Major League Baseball Health and Injury Tracking System. A separate dataset of player usage-days of rest per game, innings pitched or fielded per game, and batters faced or plate appearances per game-was used to determine the workload. We compared these usage variables between player games ≤2, ≤6, ≤12, and >12 weeks before a documented oblique strain with player games from a control group of players with no oblique strains. In a paired analysis, we compared acute (player games ≤2, ≤6, and ≤12 weeks preinjury) versus chronic (player games >12 weeks preinjury) workloads. There were 311 oblique strains in pitchers and 392 oblique strains in position players during the study period. In pitchers, more innings pitched and more batters faced were associated with a subsequent oblique strain (P < .001 for all). In position players, fewer days of rest, more innings fielded, and more plate appearances were associated with a subsequent oblique strain (P < .001 for all). Pitchers who pitched ≥7 innings per game had a 2.4-fold (95% CI, 1.4-4.9) increased risk of subsequent oblique strain compared with those who pitched 1 inning per game. The percentage of position players with a subsequent oblique strain increased by 2.1-fold (95% CI, 1.3-3.5) with >4 plate appearances compared with 1 plate appearance per game. Our analysis demonstrated that workload was associated with an increased risk of sustaining an oblique injury in professional baseball players. High workload over time was more predictive of oblique strains compared to acute increases over chronic baseline workload.

Is Workload Associated With Internal Impingement in Professional Baseball Pitchers? An Analysis of Days of Rest, Innings Pitched, and Batters Faced.

Internal impingement is a common cause of shoulder pain and dysfunction in baseball pitchers. The purpose of this study was to determine if the amount of rest days between outings, the number of innings pitched in each outing, and the number of batters faced in each outing are risk factors for internal impingement in professional baseball pitchers. It was hypothesized that a higher workload would significantly increase a pitcher's risk of developing internal impingement. Case-control study; Level of evidence, 3. All professional (Major and Minor League) baseball pitchers who were diagnosed with internal impingement between 2011 and 2017 were identified using the Major League Baseball's Health and Injury Tracking System. A separate player usage data set was used to determine workload. The authors compared workload variables (days of rest, innings pitched, and batters faced per game) between each of 4 injury-exposure groups (pitchers with documented internal impingement <2, <6, <12, and >12 weeks after a game) and a control group of pitchers with no internal impingement using Student t tests or Mann-Whitney U tests. In a within-pitcher paired analysis of the injury groups, the workload variables during 3 acute periods (<2, <6, and <12 weeks preinjury) were compared with the baseline values (>12 weeks preinjury). Overall, there were 624 professional baseball pitchers diagnosed with internal impingement during the study period. Compared with pitcher games (n = 213,964), pitchers in all 4 injury-exposure groups had significantly more innings pitched per game (P ≤ .003 for all) and faced significantly more batters per game (P < .001 for all). There were significantly more starting pitchers in each of the injury-exposure groups when compared with the controls (P < .001 for all). However, when comparing acute and baseline workloads in the pitchers diagnosed with internal impingement, there were no significant differences in the number of innings pitched, batters faced, or days of rest. This analysis revealed significantly greater pitcher workload and percentage of starting pitchers in professional baseball players diagnosed with internal impingement when compared with healthy controls. However, this injury did not seem to be associated with an acute increase in workload.

Team's average acute:chronic workload ratio correlates with injury risk in NCAA men's soccer team.

Research in multiple sports has shown that an individual's acute:chronic workload ratio (ACWR) correlates with injury. However, tailoring team trainings to each individual's ACWR is technically challenging and has not been found to decrease injury risk. To establish a more feasible method of utilizing the ACWR for injury prevention in soccer. In a National Collegiate Athletic Association (NCAA) men's soccer team, we assessed whether the team's average ACWR, as opposed to that of each individual, correlated with injuries sustained throughout the season. Injury and workload data were retrospectively evaluated for all players (n= 23) of an NCAA men's soccer team during one 18-week season. Workload data for five global positioning system (GPS)-derived workload variables (total distance, high-speed distance, accelerations, player load, and average velocity) were used to calculate the team's average daily acute and chronic workloads (accumulated load for each variable during the past 3 and 28 days, respectively), and uncoupled ACWRs (acute workload divided by chronic workload for each variable). A retrospective cohort design was used to compare the team's workloads and ACWRs on days where ≥1 injury occurred versus days where zero injuries occurred using binary logistic regression models. Trainings/games with injuries had higher acute workloads, lower chronic workloads, and higher ACWRs for all five workload variables. In multivariable analysis, risk factors for injury included a low chronic workload for total distance (odds ratio [OR] 7.23, p= .024) and an ACWR >1.4 for accelerations (OR 4.34, p= .029). The team's injury risk was greater with low distance accumulation during the chronic period and with an elevated ACWR for accelerations. Future intervention-based studies aimed at using ACWR load-management principles as a method of decreasing injury risk in soccer can consider tracking the team's average values with the goal of maintaining a consistent chronic workload for total distance and avoiding elevations in the ACWR for accelerations.

Day Type and Start Time May Influence Sleep in Adolescent Professional Football Players.

This study assessed whether scheduling (start time and day type) and workload variables influenced sleep markers (activity monitor) in professional academy footballers (n=11; 17.3±0.7 yrs) over a 10-week in-season period. Separate linear mixed regressions were used to describe the effect of start time on the previous nights sleep, and the effect of day type (match day, match day+1) and workload on subsequent sleep. Workload variables were modelled by day (day), 7-day (acute), and 28-day (chronic) periods. Sleep duration following match day+1 (400 mins; 95%CI:368-432) was significantly reduced compared to all other day types (p<0.001). Sleep onset time following match day (00:35; CI:00:04-01:12) and wake time on match day+1 (09:00; CI:08:37-09:23) were also significantly later compared to all other day types (p<0.001). Sleep duration (19.1 mins; CI:9.4-28.79), wake time (18 mins; CI:9.3-26.6), and time in bed (16.8 mins; CI:2.0-31.5) were significantly increased per hour delay in start time. When no activity was scheduled, sleep duration (37 mins; CI:18.1-55.9), sleep onset (42.1 mins; CI:28.8-56.2), and wake times (86 mins; CI:72-100) were significantly extended, relative to a 09:00 start time. Day, acute, and chronic workloads were associated with sleep onset and wake times only. Scheduled start times were associated with changes in sleep duration. Therefore, delaying start times may increase sleep in this population.

Occupational Footwear Design Influences Biomechanics and Physiology of Human Postural Control and Fall Risk

While design modifications present on work boots improve safety, they may not always provide optimal human performance during work tasks. Understanding the impact of these different design features on biomechanical and physiological postural control and locomotion variables can aid in better design modifications that can provide a safe and efficient human performance. This brief review focuses on a series of studies conducted by the current research team, that have tested three different work boots (SB: high-top steel-toed work boots; TB: high-top tactical work boots; SR: low-top slip-resistant work boots). The series of studies included testing of these work boots or combinations of them under acute and chronic simulated occupational workloads, assessing biomechanical variable such as postural stability, gait, slips, and muscle activity, as well as physiological variables such as heart rate, energy expenditure, oxygen consumption, and pain perception. The impact of each of the work boots and their design feature on postural control and locomotion are summarized from these studies’ previously published literature. Finally, work boot design suggestions for optimal human performance are provided for better work boot selection, modification, and design.

Development and assessment of an educational intervention to improve the recognition of frailty on an acute care respiratory ward

BackgroundFrailty is a robust predictor of poor outcomes among patients with chronic obstructive pulmonary disease yet is not measured in routine practice. We determined barriers and facilitators to measuring frailty...

Are acute player workloads associated with in-game performance in basketball?

To investigate associations between acute workload and in-game performance in basketball. Eight semi-professional, male basketball players were monitored during all training sessions (N = 28) and games (N = 18) across the season. External workload was determined using absolute (arbitrary units[AU]) and relative (AU·min-1) PlayerLoadTM (PL), and absolute (count) and relative (count·min-1) low-intensity, medium-intensity, high-intensity, and total Inertial Movement Analysis (IMA) events (accelerations, decelerations, changes-of-direction, and jumps). Internal workload was determined using absolute and relative Summated-Heart-Rate-Zones workload, session-rating of perceived exertion, rating of perceived exertion, and time (min) spent working > 90% of maximal heart rate. In-game performance was indicated by the player efficiency statistic. Repeated measures correlations were used to determine associations between acute workload variables (across the previous 7 days) and player efficiency. Relative PL (r = 0.13, small) and high-intensity IMA events (r = 0.13, small) possessed the strongest associations with player efficiency of the investigated workload variables (P > 0.05). All other associations were trivial in magnitude (P > 0.05). Given the trivial-small associations between all external and internal workload variables and player efficiency, basketball practitioners should not rely solely on monitoring acute workloads to determine performance potential in players.

External workload patterns of injured elite Rugby League players before and after return to play

Introduction: Return to play protocols (RTP) are imperative to ensuring injured athletes are adequately prepared to return to competition without re-injury. This study aimed to characterise the acute and chronic external workloads achieved by injured National Rugby League (NRL) athletes before and after RTP. Methods: Global positioning system (GPS) workload variables were investigated for 10 injured NRL athletes (n= 10, mean age 23.6 years, backs n=5, forwards n=5) two weeks before and after RTP. All athletes had sustained injuries of ≥14-day severity. GPS variables included total (TD) and high to very-high speed running (V-VHSR) distance (≥18km/h), accumulated absolute acceleration (acceleration load), and number of repeat high-intensity efforts (RHIE). Both acute (current week) and chronic (4-week mean) workload was determined for each observation week and analysed using linear mixed models that included time as a fixed effect, mean-centred injury severity as a covariate, and participant as a random effect. Effect magnitude was determined by percentage difference and 95% confidence interval. Results: Mean injury severity was 24 days (range: 14-49 days) and did not significantly moderate any acute (p≥0.614) or chronic (p≥0.272) workload variable. Time significantly affected acute TD, acceleration load, and RHIE (p≤0.038), but not VVHSR distance (p=0.070). Acute workload was highest during the week of RTP for all variables, with an 86 ±51% (TD), 41 ±37% (V-VHSR), 95 ±50% (acceleration load), and 116 ±72% (RHIE) increase compared to the previous rehabilitation week. Time significantly affected chronic RHIE (p=0.038), but not TD (p=0.315), V-VHSR (p=0.931), or acceleration load (p=0.213). Chronic workload was highest during the second week after RTP, with the three previous weeks being decreased by -13 to 17 ±18% (TD), -7 to -8 ±24% (V-VHSR), -14 to -18 ±17% (acceleration load), and -22 to -28 ±19% (RHIE). Discussion: The acute external workloads of injured NRL athletes demonstrated large increases during the RTP week which may increase the likelihood of re-injury. In contrast, chronic workload was relatively stable before and after RTP for all external workload variables except RHIE which was low until 2 weeks after RTP. Greater focus on RHIE workload in the lead up to RTP may be needed to ensure adequate exposure to that aspect of rugby league. Conflict of interest statement: my co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.

Workload and Noncontact Musculoskeletal Injury in Collegiate Swimmers: A Prospective Cohort Study.

Swimmers are known for experiencing high training loads and a high incidence of overuse injuries, but few researchers have investigated the relationship between the two at the collegiate level. To determine the association between workload and noncontact musculoskeletal injury in collegiate swimmers. Prospective cohort study. College natatorium. A total of 37 National Collegiate Athletic Association Division III swimmers, 26 uninjured (age = 19 years [interquartile range = 3 years], height = 175 ± 11 cm, mass = 70.2 ± 10 kg) and 11 injured (age = 19 years [interquartile range = 3 years], height = 173 ± 9 cm, mass = 69.4 ± 13.5 kg) individuals. Logistic regression using generalized estimating equations was conducted to calculate odds ratios (ORs) with 95% CIs for injury relative to high workloads and high acute:chronic workload ratio (ACWRs). Injury rates for several ranges of workloads and ACWRs were also calculated. A total of 11 participants (29.7%) sustained 12 injuries, with 7 injuries occurring during the participants' winter training trip. Injury was associated with high acute workloads (OR = 27.1; 95% CI = 8.2, 89.8) and high ACWRs (OR = 25.1; 95% CI = 7.7, 81.4) but not high chronic (OR = 2.6; 95% CI = 0.3, 20.0) or overall (OR = 1.00; 95% CI = 0.99, 1.01) workloads. High acute workloads (>37.2 km/wk) and ACWRs (>1.56) increased the injury rate from ≤1% to 15% and 14%, respectively, compared with all lower acute workloads and ACWRs. Collegiate swimmers tolerated high workloads spread out during the season. However, caution should be used when prescribing high acute workloads and high ACWRs (eg, winter training trip) because of the increased odds of injury.

Editorial: Acute: Chronic Workload Ratio: Is There Scientific Evidence?

The scientific monitoring of athletes is fundamental to determine and understand the individual biological responses to training (Halson, 2014). In elite sports, it is crucial to regularly monitor training and performance to detect biopositive or negative responses that can be used to effectively program training according to the needs of each athlete (Bourdon et al., 2017). Moreover, workload monitoring can also help to assess fatigue and indicate the need for recovery in different physically demanding situations to ultimately avoid injuries (Halson, 2014). As there is evidence that lower injury rates are associated with higher team sport performances (Eirale et al., 2013), sport scientists and medical staff should regularly and accurately evaluate athletes' injury risk using workload measures (Halson, 2014). Based on Banister et al. (1975) fitness and fatigue model, Gabbett et al. (2016) introduced the concept of the acute:chronic workload ratio (ACWR) with acute workload hypothetically representing the fatigue component and chronic workload the fitness component of Banister's model (Figure 1). ACWR allows individualized performance development and injury prevention using the relation between acute to chronic workload data. For this purpose, internal (e.g., heart rate, session-rate of perceived exertion [sRPE] × duration) and external (e.g., performance measures, tracking variables such as running speed and/or acceleration using Global Positioning Systems [GPS]) load measures should be collected to compute ACWR during training and competition (Malone et al., 2017). It has previously been recommended to determine the ratio between acute (training load accumulated during the last 7 days) and chronic (mean training load over the previous 3 to 6 weeks) workloads (Gabbett et al., 2016; Gabbett and Whiteley, 2017). The underlying rationale is that athletes' physical fitness develops adequately if the chronic load progressively increases to high levels while the acute load remains below, similar to, or slightly above the chronic workload (i.e., ACWR range between 0.8 and 1.3). Conversely, the athlete is considered not well-prepared and likely at an increased risk of sustaining acute or overuse injuries if the acute workload exceeds the chronic load (i.e., ACWR ≥ 1.5) (Malone et al., 2017; Windt and Gabbett, 2017). Open in a separate window Figure 1 Conceptual model for developing athlete monitoring systems according to the fitness-fatigue model using the acute: chronic workload (ACWR) approach and internal/external workload measures. While the fitness component is comparable to chronic workload (e.g., 28 days rolling average workload), fatigue is comparable to acute workload (e.g., 7 days rolling average workload) (adapted from Coutts et al., 2018).

Association of acute and chronic workloads with injury risk in high-performance junior tennis players

This study examined the association and predictive ability of several markers of internal workload on risk of injury in high-performance junior tennis players. Fifteen young, high-level tennis players (9 males, 6 females; age: 17.2 ± 1.1 years; height: 178.5 ± 8.7 cm; mass: 68.1 ± 4.8 kg) participated in this investigation. Data on injury epidemiology and internal workload during training were obtained for one competitive season. The session-rating of perceived exertion (s-RPE) was used to calculate internal workload markers in absolute (acute workload and chronic workload for 2-weeks, 3-weeks and 4-weeks) and relative terms (acute:chronic workload ratios [ACWR] for 2-weeks, 3-weeks and 4-weeks). Associations and diagnostic power for predicting tennis injuries were examined through generalised estimating equations and receiver operating characteristics analyses. During the season, a total of 40 injuries were recorded, corresponding to 3.5 injuries per 1000 h of tennis practice. The acute workload was highly associated with injury incidence (P=0.04), as injury risk increased by 1.62 times (95% CI: 1.01–2.62) for every increase of 1858.7 arbitrary units (AU) of the workload during the most recent training week. However, acute workload was a poor predictor of injury, and associations between injury and internal workload markers were weak (all P>0.05). These findings demonstrate an association between high values of acute workload and the risk of injury in high-level tennis players. However, a high acute workload is only one of the many factors associated with injury, and by itself, has low predictive ability for injury.

Increase in the Acute:Chronic Workload Ratio relates to Injury Risk in Competitive Runners.

Injuries of runners reduce the ability to train and hinder competing. Literature shows that the relation between potential risk factors and injuries are not definitive, limited, and inconsistent. In team sports, workload derivatives were identified as risk factors. However, there is an absence of literature in running on workload derivatives. This study used the workload derivatives acute workload, chronic workload, and acute: chronic workload ratios to investigate the relation between workload and injury risk in running. Twenty-three competitive runners kept a daily training log for 24 months. The runners reported training duration, training intensity and injuries. One-week (acute) and 4-week (chronic) workloads were calculated as the average of training duration multiplied by training intensity. The acute:chronic workload ratio was determined dividing the acute and chronic workloads. Results show that a fortnightly low increase of the acute:chronic workload ratio (0.10-0.78) led to an increased risk of sustaining an injury (p<0.001). Besides, a low increase of the acute:chronic workload ratio (0.05-0.62) between the second week and third week before an injury showed an association with increased injury risk (p=0.013). These findings demonstrate that the acute:chronic workload ratio relates to injury risk.

A prospective cohort study on the acute:chronic workload ratio in relation to injuries in high level eventing horses: A comprehensive 3-year study

In human sport science, the acute:chronic workload (ACWR) ratio is used to monitor an athlete’s preparedness for competition and to assess injury risks. The aim of this study was to investigate whether acute and chronic workload calculations for external and internal loads (e.g. high-speed work distance and associated exertional effort) were associated with injury risk in elite eventing horses and to identify workloads performed by horses competing in different competition and at different fitness levels.Training load and injury data were collected from 58 international eventing horses (CCI2*–CCI5* level) over 1–3 years. A total of 94 individual competition seasons were monitored. During this period, heart rate (HR; beat/min) and GPS data were collected of all their conditional training sessions and competitions. External load was determined as the distance (m) covered at high speed (HS11High speed = HS, velocity between 6.6 m/s and 9.5 m/s ; velocity between 6.6 and 9.5 m/s), and sprint speed (SS22Sprint speed = SS, velocity above 9.5 m/s ; velocity>9.5 m/s). Internal load was calculated for HS and SS, using individualized training impulses (TRIMP33Training impulses; TRIMP (represented in AU) ;AU). For internal and external workload HS and SS the acute (1-week) and chronic (4-week) workloads were calculated and ACWR44Acute:chronic workload ratio: ACWR determined. The injury data in relation to ACWR was modelled with a multilevel logistic regression. Akaike’s information criterion was used for model reduction.Sixty-four soft tissue injuries were registered from a total of 2300 training sessions and competitions. External and internal workload at HS and SS were significantly affected by the year and fitness level of horses. Competition level and year significantly affected the distances covered at SS. The ACWR of high-speed distance of the present week (OR; 0.133, 95 % CI; 0.032, 0.484) and the previous week (OR 3.951, 95 % CI; 1.390, 12.498) were significantly associated with injury risk. Competition level and chronic workload had no significant effect on injuries.In agreement with findings in human athletes, acute spikes of workload in eventing horses increased the risk of injury. Evaluation of horses’ workload can be used to design and effectively monitor training programs and can help to improve equine welfare by reducing injury risk.

Relationships Among PlayerLoad, High-Intensity Intermittent Running Ability, and Injury Risk in Professional Rugby League Players.

To examine relationships among physical performance, workload, and injury risk in professional rugby league players. Maximal-effort (n = 112) and submaximal (n = 1084) running performances of 45 players were recorded from 1 club over 2 consecutive seasons. Poorer and better submaximal running performance was determined by higher and lower exercise heart rates, respectively. Exponentially weighted moving averages and daily rolling averages were used to assess microtechnology-derived acute and chronic field-based workloads. The associations among within-individual submaximal running performance, workload, and noncontact lower-limb injury were then investigated. The injury risk associated with poorer submaximal performance was "likely" greater than stable (relative risk = 1.8; 90% confidence interval, 0.9-3.7) and better submaximal performance (relative risk = 2.0; 90% confidence interval, 0.9-4.4). Compared with greater submaximal performance, poorer performance was associated with lower chronic workloads (effect size [d] = 0.82 [0.13], large) and higher acute:chronic workload ratios (d = 0.49 [0.14], small). Chronic workload demonstrated a "nearly perfect" positive relationship with maximal-effort running performance (exponentially weighted moving average, R2 = .91 [.15]; rolling average, R2 = .91 [.14]). At acute:chronic workload ratios >1.9, no differences in injury risk were found between rolling average and exponentially weighted moving average methods (relative risk = 1.1; 90% confidence interval, 0.3-3.8; unclear). Reductions in submaximal running performance are related with low chronic workloads, high acute:chronic workload ratios, and increased injury risk. These findings demonstrate that a submaximal running assessment can be used to provide information on physical performance and injury risk in professional rugby league players.

To Couple or not to Couple? For Acute:Chronic Workload Ratios and Injury Risk, Does it Really Matter?

We examined the association between coupled and uncoupled acute:chronic workload ratios (ACWR) and injury risk in a cohort of 28 elite cricket fast bowlers (mean±SD age, 26±5 yr). Workloads were estimated using the session rating of perceived exertion (session-RPE). Coupled ACWRs were calculated using a 1-week acute workload and 4-week chronic workload (acute workload was included in the chronic workload calculation), whereas uncoupled ACWRs used the most recent 1-week acute workload and the prior 3-week chronic workload (acute workload was not included in the chronic workload calculation). A nearly perfect relationship (R2=0.99) was found between coupled and uncoupled ACWRs. Using a percentile rank method, no significant differences in injury risk were found between the coupled and uncoupled ACWR. Higher ACWRs were associated with increased injury likelihood for both coupled and uncoupled methods, however there were no significant differences in injury risk between coupled and uncoupled ACWRs. Our data demonstrates that both coupled and uncoupled ACWRs produce the same injury likelihoods. Furthermore, our results are consistent with previous studies: higher ACWRs are associated with greater risk, irrespective of whether acute and chronic workloads are coupled or uncoupled.

Association of Daily Workload, Wellness, and Injury and Illness During Tours in International Cricketers.

To examine the relationship between player internal workloads, daily wellness monitoring, and injury and illness in a group of elite adolescent cricketers during overseas competitions. A total of 39 male international adolescent cricketers (17.5 [0.8]y) took part in the study. Data were collected over 5 tours across a 3-y period (2014-2016). Measures of wellness were recorded and daily training loads were calculated using session rating of perceived exertion. The injury and illness status of each member of the squad was recorded daily. Acute and chronic workloads were calculated using 3-d and 14-d moving averages. Acute workloads, chronic workloads, and acute chronic workload ratios were independently modeled as fixed effects predictor variables. In the subsequent week, a high 3-d workload was significantly associated with an increased risk of injury (relative risk = 2.51; CI = 1.70-3.70). Similarly, a high 14-d workload was also associated with an increased risk of injury (relative risk = 1.48; CI = 1.01-2.70). Individual differences in the load-injury relationship were also found. No clear relationship between the acute chronic workload ratios and injury risk was found, but high chronic workloads combined with high or low acute chronic workload ratios showed an increased probability of injury compared with moderate chronic workloads. There were also trends for sleep quality and cold symptoms worsening the week before an injury occurred. Although there is significant individual variation, short-term high workloads and change in wellness status appear to be associated with injury risk.

The acute:chonic workload ratio in relation to injury risk in professional soccer.

To examine the association between combined sRPE measures and injury risk in elite professional soccer. Observational cohort study. Forty-eight professional soccer players (mean±SD age of 25.3±3.1 yr) from two elite European teams were involved within a one season study. Players completed a test of intermittent-aerobic capacity (Yo-YoIR1) to assess player's injury risk in relation to intermittent aerobic capacity. Weekly workload measures and time loss injuries were recorded during the entire period. Rolling weekly sums and week-to-week changes in workload were measured, allowing for the calculation of the acute:chronic workload ratio, which was calculated by dividing the acute (1-weekly) and chronic (4-weekly) workloads. All derived workload measures were modelled against injury data using logistic regression. Odds ratios (OR) were reported against a reference group. Players who exerted pre-season 1-weekly loads of ≥1500 to ≤2120AU were at significantly higher risk of injury compared to the reference group of ≤1500AU (OR=1.95, p=0.006). Players with increased intermittent-aerobic capacity were better able to tolerate increased 1-weekly absolute changes in training load than players with lower fitness levels (OR=4.52, p=0.011). Players who exerted in-season acute:chronic workload ratios of >1.00 to <1.25 (OR=0.68, p=0.006) were at significantly lower risk of injury compared to the reference group (≤0.85). These findings demonstrate that an acute:chronic workload of between 1.00 and 1.25 is protective for professional soccer players. A higher intermittent-aerobic capacity appears to offer greater injury protection when players are exposed to rapid changes in workload in elite soccer players. Moderate workloads, coupled with moderate-low to moderate-high acute:chronic workload ratios, appear to be protective for professional soccer players.

Accumulated workloads and the acute:chronic workload ratio relate to injury risk in elite youth football players

AimThe purpose of this study was to investigate the relationship between physical workload and injury risk in elite youth football players.MethodsThe workload data and injury incidence of 32 players were...

Assessment of Workload and its Effects on Performance and Injury in Elite Cricket Fast Bowlers.

Cricket is distinctly positioned in the world of elite sports because three different formats now exist, each with characteristically different workload requirements. Fast bowlers have greater match-play workload requirements and are at greater injury risk than other positions. An update on the current cricket literature regarding fast bowling match-play physiology, workload, and injury is required to demonstrate the extent to which workload is related to performance and injury in elite fast bowlers since the introduction of 20-over cricket in 2005. The current review examined articles published in English with data collected from 2005 onwards pertaining to in situ cricket fast bowling physiology, match play, injury, and workload. Four databases were searched using the combinations of the following keywords: 'cricket' and 'bowl', inclusive of 'pace', 'fast', 'medium', or 'seam' bowling. Articles from 2005 onwards with male participants, high-performing or elite, and fast bowlers in the game of cricket were considered for inclusion. Only workload assessments captured in a field setting were included. A total of 751 articles were identified. Exclusions included 527 duplicates, papers pre-2005, review articles, and abstracts. A further 185 articles were excluded after review of titles and abstracts that were deemed to be outside the scope of research or population. The full texts of 39 articles were reviewed, with only 17 included in this systematic review. In five articles reviewed, fast bowlers had a greater workload than other player types. Bowling workload history was reviewed in seven articles and appeared to have a complex interaction with likelihood of injury and injury type. Fast bowling workload has a well recognised relationship with injury and performance. Although monitoring acute and chronic workloads of fast bowlers remains the most ideal method for identifying preparedness and injury likelihood in fast bowlers, complexities exist that make the systematic prescription of bowling workloads difficult. Advances in technology to monitor workloads may provide further insight into the intensity and workloads of fast bowlers. PROSPERO registration number: CRD42015032466.