Incidence of injuries in high school softball and baseball players

Context:

Participation in high school sports has grown 16.1% over the last decade, but few studies have compared the overall injury risks in girls'' softball and boys'' baseball.

Objective:

To examine the incidence of injury in high school softball and baseball players.

Design:

Cohort study.

Setting:

Greenville, South Carolina, high schools.

Patients or Other Participants:

Softball and baseball players (n = 247) from 11 high schools.

Main Outcome Measure(s):

Injury rates, locations, types; initial or subsequent injury; practice or game setting; positions played; seasonal trends.

Results:

The overall incidence injury rate was 4.5/1000 athlete-exposures (AEs), with more injuries overall in softball players (5.6/1000 AEs) than in baseball players (4.0/1000 AEs). Baseball players had a higher initial injury rate (75.9/1000 AEs) than softball players (66.4/1000 AEs): rate ratio (RR) = 0.88, 95% confidence interval (CI) = 0.4, 1.7. The initial injury rate was higher than the subsequent injury rate for the overall sample (P < .0001) and for softball (P < .0001) and baseball (P < .001) players. For both sports, the injury rate during games (4.6/1000 AEs) was similar to that during practices (4.1/1000 AEs), RR = 1.22, 95% CI = 0.7, 2.2. Softball players were more likely to be injured in a game than were baseball players (RR = 1.92, 95% CI = 0.8, 4.3). Most injuries (77%) were mild (3.5/1000 AEs). The upper extremity accounted for the highest proportion of injuries (63.3%). The incidence of injury for pitchers was 37.3% and for position players was 15.3%. The rate of injury was highest during the first month of the season (7.96/1000 AEs).

Conclusions:

The incidence of injury was low for both softball and baseball. Most injuries were minor and affected the upper extremity. The injury rates were highest in the first month of the season, so prevention strategies should be focused on minimizing injuries and monitoring players early in the season.     

Prediction of core and lower extremity strains and sprains in collegiate football players: a preliminary study

Context:

Poor core stability is believed to increase vulnerability to uncontrolled joint displacements throughout the kinetic chain between the foot and the lumbar spine.

Objective:

To assess the value of preparticipation measurements as predictors of core or lower extremity strains or sprains in collegiate football players.

Design:

Cohort study.

Setting:

National Collegiate Athletic Association Division I Football Championship Subdivision football program.

Patients or Other Participants:

All team members who were present for a mandatory physical examination on the day before preseason practice sessions began (n  =  83).

Main Outcome Measure(s):

Preparticipation administration of surveys to assess low back, knee, and ankle function; documentation of knee and ankle injury history; determination of body mass index; 4 different assessments of core muscle endurance; and measurement of step-test recovery heart rate. All injuries were documented throughout the preseason practice period and 11-game season. Receiver operating characteristic analysis and logistic regression analysis were used to identify dichotomized predictive factors that best discriminated injured from uninjured status. The 75th and 50th percentiles were evaluated as alternative cutpoints for dichotomization of injury predictors.

Results:

Players with ≥2 of 3 potentially modifiable risk factors related to core function had 2 times greater risk for injury than those with <2 factors (95% confidence interval  =  1.27, 4.22), and adding a high level of exposure to game conditions increased the injury risk to 3 times greater (95% confidence interval  =  1.95, 4.98). Prediction models that used the 75th and 50th percentile cutpoints yielded results that were very similar to those for the model that used receiver operating characteristic-derived cutpoints.

Conclusions:

Low back dysfunction and suboptimal endurance of the core musculature appear to be important modifiable football injury risk factors that can be identified on preparticipation screening. These predictors need to be assessed in a prospective manner with a larger sample of collegiate football players.     

Rate and risk of anterior cruciate ligament injury among sportswomen in Slovenia

Context:

Anterior cruciate ligament (ACL)-injury rate is greater among female athletes than among male athletes.

Objective:

To investigate the rate and risk of ACL injury among Slovenian sportswomen playing professional basketball, team handball, or volleyball.

Design:

Prospective cohort study.

Setting:

The Slovenian National Organizations of basketball, team handball, and volleyball.

Patients or Other Participants:

During the 2003–2004 season, we prospectively followed 585 Slovenian sportswomen registered in the Slovenian National Organizations of basketball, team handball, and volleyball.

Main Outcome Measure(s):

We asked sportswomen and coaches to document the occurrence of every significant traumatic knee injury requiring medical attention. Injury rate and injury risk were calculated for sportswomen in each sport group. To calculate injury rate, we estimated the average exposure of each sportswoman during the research period.

Results:

During the 2003–2004 season, 585 Slovenian sportswomen sustained 12 ACL injuries. The ACL-injury risk was different in athletes participating in the various sports, with basketball players having the greatest ACL-injury risk and volleyball players having the lowest ACL-injury risk (P  =  .04). The risk of ACL injury among Slovenian sportswomen was 2.1 per 100 athletes (95% confidence interval  =  0.9, 3.2), whereas the rate of ACL injury was 0.037 per 1000 exposure hours (95% confidence interval  =  0.016, 0.06).

Conclusions:

Overall differences in injury risk were found among sports, but no differences were noted among divisions within sports. No differences for injury rate were observed between or within sports. The rate and risk of ACL injury among Slovenian sportswomen are high, with basketball players having the greatest ACL-injury risk.     

National Collegiate Athletic Association Division I Football Players' Perceptions of Women in the Athletic Training Room Using a Role Congruity Framework

Context:

Previous researchers have demonstrated that male and female athletes feel more comfortable with treatment by a same-sex athletic trainer for sex-specific injuries and conditions.

Objective:

To address football players'' comfort with care provided by same-sex and opposite-sex athletic trainers for sex-specific and non–sex-specific injuries and conditions through the lens of role congruity theory.

Design:

Cross-sectional study for the quantitative data and qualitative study for the qualitative data.

Setting:

Two National Collegiate Athletic Association Division I Football Bowl Series university football programs.

Patients or Other Participants:

Male football players within the 2 university programs.

Data Collection and Analysis:

We replicated existing methods and an existing survey to address male football players'' comfort levels. Additionally, an open-ended question was used to determine male football players'' perceptions of female athletic trainers. Paired-samples t tests were conducted to identify differences between the responses for the care given by a male athletic trainer and for the care given by a female athletic trainer. Three categories were analyzed: general medical conditions, psychological conditions, and sex-specific injuries. The qualitative data were coded and analyzed using content analysis.

Results:

Male football players were more comfortable with treatment by a male athletic trainer (mean  =  3.61 ± 1.16) for sex-specific injuries and conditions than they were with treatment by a female athletic trainer (mean  =  2.82 ± 1.27; P < .001). No significant results were found for comfort with overall psychological conditions, although a female athletic trainer was preferred over a male athletic trainer for the treatment of depression (mean  =  3.71 ± 1.07 versus mean  =  3.39 ± 1.16, respectively; P < .001). Qualitative data provided support for role congruity theory.

Conclusions:

Both quantitative and qualitative evidence were provided for the support of role congruity theory.     

Quadriceps Activation Following Knee Injuries: A Systematic Review

Context:

Arthrogenic muscle inhibition is an important underlying factor in persistent quadriceps muscle weakness after knee injury or surgery.

Objective:

To determine the magnitude and prevalence of volitional quadriceps activation deficits after knee injury.

Data Sources:

Web of Science database.

Study Selection:

Eligible studies involved human participants and measured quadriceps activation using either twitch interpolation or burst superimposition on patients with knee injuries or surgeries such as anterior cruciate ligament deficiency (ACLd), anterior cruciate ligament reconstruction (ACLr), and anterior knee pain (AKP).

Data Extraction:

Means, measures of variability, and prevalence of quadriceps activation (QA) failure (<95%) were recorded for experiments involving ACLd (10), ACLr (5), and AKP (3).

Data Synthesis:

A total of 21 data sets from 18 studies were initially identified. Data from 3 studies (1 paper reporting data for both ACLd and ACLr, 1 on AKP, and the postarthroscopy paper) were excluded from the primary analyses because only graphical data were reported. Of the remaining 17 data sets (from 15 studies), weighted mean QA in 352 ACLd patients was 87.3% on the involved side, 89.1% on the uninvolved side, and 91% in control participants. The QA failure prevalence ranged from 0% to 100%. Weighted mean QA in 99 total ACLr patients was 89.2% on the involved side, 84% on the uninvolved side, and 98.5% for the control group, with prevalence ranging from 0% to 71%. Thirty-eight patients with AKP averaged 78.6% on the involved side and 77.7% on the contralateral side. Bilateral QA failure was commonly reported in patients.

Conclusions:

Quadriceps activation failure is common in patients with ACLd, ACLr, and AKP and is often observed bilaterally.     

Explosive Strength Imbalances in Professional Basketball Players

Context:

Despite the high rate of lower limb injuries in basketball players, studies of the dominant-limb effect in elite athletes often neglect injury history.

Objective:

To determine lower limb explosive-strength asymmetries in professional basketball players compared with junior basketball players and control participants.

Design:

Cohort study.

Setting:

Academic medical institution.

Patients or Other Participants:

15 professional basketball players, 10 junior basketball players, and 20 healthy men.

Main Outcome Measure(s):

We performed an isokinetic examination to evaluate the knee extensor (Ext) and flexor (Fl) concentric peak torque at 60°·s⁻¹ and 240°·s⁻¹ and (Fl only) eccentric peak torque at 30°·s⁻¹ and 120°·s⁻¹. Functional evaluation included countermovement jump, countermovement jump with arms, 10-m sprint, single-leg drop jump, and single-leg, 10-second continuous jumping. Variables were compared among groups using analysis of variance or a generalized linear mixed model for bilateral variables.

Results:

The 2 groups of basketball players demonstrated better isokinetic and functional performances than the control group did. No differences in functional or relative isokinetic variables were noted between professional and junior basketball players. Professional players with a history of knee injury failed to reach normal knee extensor strength at 60°·s⁻¹. Knee Ext (60°·s⁻¹) and Fl (eccentric 120°·s⁻¹) torque values as well as 10-second continuous jumping scores were higher in those professional players without a history of knee injury than those with such a history. Compared with the group without a history of knee injury, the group with a history of knee injury maintained leg asymmetry ratios greater than 10% for almost all isokinetic variables and more than 15% for unilateral functional variables.

Conclusions:

The relative isokinetic and functional performances of professional basketball players were similar to those of junior players, with no dominant-side effect. A history of knee injury in the professional athlete, however, was reflected in bilateral isokinetic and functional asymmetries and should be considered in future studies of explosive strength.     

Thigh Muscle Activity,Knee Motion,and Impact Force During Side-Step Pivoting in Agility-Trained Female Basketball Players

Context:

Improving neuromuscular control of hamstrings muscles might have implications for decreasing anterior cruciate ligament injuries in females.

Objective:

To examine the effects of a 6-week agility training program on quadriceps and hamstrings muscle activation, knee flexion angles, and peak vertical ground reaction force.

Design:

Prospective, randomized clinical research trial.

Setting:

Sports medicine research laboratory.

Patients or Other Participants:

Thirty female intramural basketball players with no history of knee injury (age  =  21.07 ± 2.82 years, height  =  171.27 ± 4.66 cm, mass  =  66.36 ± 7.41 kg).

Intervention(s):

Participants were assigned to an agility training group or a control group that did not participate in agility training. Participants in the agility training group trained 4 times per week for 6 weeks.

Main Outcome Measure(s):

We used surface electromyography to assess muscle activation for the rectus femoris, vastus medialis oblique, medial hamstrings, and lateral hamstrings for 50 milliseconds before initial ground contact and while the foot was in contact with the ground during a side-step pivot maneuver. Knee flexion angles (at initial ground contact, maximum knee flexion, knee flexion displacement) and peak vertical ground reaction force also were assessed during this maneuver.

Results:

Participants in the training group increased medial hamstrings activation during ground contact after the 6-week agility training program. Both groups decreased their vastus medialis oblique muscle activation during ground contact. Knee flexion angles and peak vertical ground reaction force did not change for either group.

Conclusions:

Agility training improved medial hamstrings activity in female intramural basketball players during a side-step pivot maneuver. Agility training that improves hamstrings activity might have implications for reducing anterior cruciate ligament sprain injury associated with side-step pivots.     

Treatment of osteochondral injuries with platelet gel

OBJECTIVES:

Treatments for injured articular cartilage have not advanced to the point that efficient regeneration is possible. However, there has been an increase in the use of platelet-rich plasma for the treatment of several orthopedic disorders, including chondral injuries. Our hypothesis is that the treatment of chondral injuries with platelet gel results in higher-quality repair tissue after 180 days compared with chondral injuries not treated with gel.

METHODS:

A controlled experimental laboratory study was performed on 30 male rabbits to evaluate osteochondral injury repair after treatment with or without platelet gel. Osteochondral injuries were surgically induced in both knees of each rabbit at the medial femoral condyle. The left knee injury was filled with the platelet gel, and the right knee was not treated. Microscopic analysis of both knee samples was performed after 180 days using a histological grading scale.

RESULTS:

The only histological evaluation criterion that was not significantly different between treatments was metachromasia. The group that was treated with platelet gel exhibited superior results in all other criteria (cell morphology, surface regularity, chondral thickness and repair tissue integration) and in the total score.

CONCLUSION:

The repair tissue was histologically superior after 180 days in the study group treated with platelet gel compared with the group of untreated injuries.     

Patients With Ice Hockey Injuries Presenting to US Emergency Departments, 1990�C2006

Context:

Although the number of US ice hockey participants doubled from 1990 to 2006, no nationally representative studies have examined US ice hockey injuries among participants of all ages during this period.

Objective:

To describe patients with ice hockey injuries presenting to a representative sample of US emergency departments (EDs) from 1990 through 2006.

Design:

Prospective injury surveillance study.

Setting:

The US Consumer Product Safety Commission collects data from 100 nationally representative EDs via the National Electronic Injury Surveillance System (NEISS).

Patients or Other Participants:

Individuals injured while playing ice hockey and presenting to a NEISS-affiliated ED from 1990 through 2006.

Main Outcome Measure(s):

Incidence and patterns of ice hockey–related injuries.

Results:

From 1990 through 2006, 8228 patients with ice hockey–related injuries presented to NEISS-affiliated EDs, representing an estimated 302 368 ice hockey–related injuries sustained nationally during this time. Injuries occurred predominantly among males (93.5%). More than half of the injured were aged 9 to 14 years (28.9%) or 15 to 18 years (30.1%), and injury incidence in these age groups increased over the study period (P  =  .009 and P < .001, respectively). The most commonly injured body sites were the face (19.1%), wrist/hand/finger (14.1%), shoulder/upper arm (13.8%), and lower leg/ankle/foot (11.1%). Lacerations (27.0%), contusions/abrasions (23.6%), fractures (17.3%), and sprains/strains (16.9%) were the most common injuries. Falls (16.5%), contact with boards (13.6%), and contact with stick (13.0%) were the most common injury mechanisms. Compared with those aged 9 to 18 years, those aged 2 to 8 years and those older than 18 years sustained larger proportions of face (injury proportion ratio [IPR]  =  2.66; 95% confidence interval [CI]  =  2.29, 3.08) and mouth (IPR  =  4.34; 95% CI  =  2.87, 6.56) injuries. Concussions were more common among those aged 2 to 18 years (9.0%) than in those who were older than 18 years (3.7%) (IPR  =  2.47; 95% CI  =  1.75, 3.49).

Conclusions:

Ice hockey injury patterns vary by age and sex. Our findings indicate that many trips to the ED might be prevented by using protective equipment appropriately.     

Comparison of recovery strategies on maximal force-generating capacity and electromyographic activity level of the knee extensor muscles

Context:

With regard to intermittent training exercise, the effects of the mode of recovery on subsequent performance are equivocal.

Objective:

To compare the effects of 3 types of recovery intervention on peak torque (PT) and electromyographic (EMG) activity of the knee extensor muscles after fatiguing isokinetic intermittent concentric exercise.

Design:

Crossover study.

Setting:

Research laboratory.

Patients or Other Participants:

Eight elite judo players (age = 18.4 ± 1.4 years, height = 180 ± 3 cm, mass = 77.0 ± 4.2 kg).

Interventions :

Participants completed 3 randomized sessions within 7 days. Each session consisted of 5 sets of 10 concentric knee extensions at 80% PT at 120°/s, with 3 minutes of recovery between sets. Recovery interventions were passive, active, and electromyostimulation. The PT and maximal EMG activity were recorded simultaneously while participants performed isokinetic dynamometer trials before and 3 minutes after the resistance exercise.

Main Outcome Measure(s):

The PT and maximal EMG activity from the knee extensors were quantified at isokinetic velocities of 60°/s, 120°/s, and 180°/s, with 5 repetitions at each velocity.

Results:

The reduction in PT observed after electromyo-stimulation was less than that seen after passive (P < .001) or active recovery (P < .001). The reduction in PT was less after passive recovery than after active recovery (P < .001). The maximal EMG activity level observed after electromyostimulation was higher than that seen after active recovery (P < .05).

Conclusions:

Electromyostimulation was an effective recovery tool in decreasing neuromuscular fatigue after high-intensity, intermittent isokinetic concentric exercise for the knee extensor muscles. Also, active recovery induced the greatest amount of neuromuscular fatigue.     

Core temperature and sweat responses in professional women's tennis players during tournament play in the heat

Context:

Tennis is often played in hot, humid environments, intensifying the thermoregulatory strain placed on the athletes. As a safety measure, some tennis organizations allow for a 10-minute break in play between the second and third sets when environmental conditions are extreme. However, the actual effect of these breaks in reducing core temperature is unknown.

Objective:

To determine change in core temperature after a 10-minute break in play and assess fluid balance in professional female tennis players during tournament matches in the heat.

Design:

Cross-sectional study.

Setting:

A Women''s Tennis Association Tour–sanctioned outdoor tournament on hard courts under hot conditions (30.3°C ± 2.3°C).

Patients or Other Participants:

Seven professional tennis players.

Main Outcome Measure(s):

Change in core temperature after a 10-minute break in tournament play, fluid intake, and sweat losses during match play.

Results:

Core temperature was reduced from 38.92°C to 38.67°C (change of −0.25°C ± 0.20°C) when a break was taken (P  =  .02). Mean sweat rate during match play was 2.0 ± 0.5 L/h. During that time, mean fluid intake was 1.5 ± 0.5 L/h, resulting in a 1.2% ± 1.0% reduction in body mass.

Conclusions:

Female professional tennis players are subjected to high heat loads during match play in hot environments. However, a 10-minute break in play decreased core temperature in 6 of 7 players by an average of 0.25°C, indicating that the break provides practical benefits in the field. Furthermore, although mean sweat rate in this group of female tennis players was high, most athletes were still able to minimize mass loss to less than 2% of their prematch weight.     

The effects of one-half of a soccer match on the postural stability and functional capacity of the lower limbs in young soccer players

OBJECTIVE:

Most injuries occur during the final 15 minutes of each half of a soccer match, suggesting that physical exertion may influence changes in neuromuscular control and the body''s ability to stabilize the joints of the lower extremities. The aim of this study was to analyze the effects of one-half of a soccer match on the functional capacity and stability of the lower limbs in young soccer players.

METHODS:

We analyzed 27 soccer players by evaluating the functional capacity of their lower limbs using the hop test protocol and their level of postural stability using the Biodex Stability System. The evaluations were performed before and after 45 minutes of game time.

RESULTS:

After the match, there was a decrease in the overall stability index (OSI) (F_(1,23) = 5.64, p = 0.026) and the anterior-posterior stability index (APSI) (F_(1,23) = 5.24,p = 0.032). In the single and triple hop tests, there was a higher functional capacity in the dominant limb compared to the non-dominant limb in the pre- and post-game comparisons.

CONCLUSION:

The results of this study show that there is a decrease in the stability of the lower limbs in young soccer players after a 45 minutes soccer match, but the same result was not found for the functional capacity.     

Ice Hockey Injuries in a Japanese Elite Team: A 3-Year Prospective Study

Context:

As the Asian Ice Hockey League gradually expands and becomes more competitive, ice hockey-related injuries may increase. However, no reports have been published on ice hockey injuries in Japan, including the method of injury and the daily supervision of the players during the regular season.

Objective:

To prospectively study the incidence, types, and mechanisms of ice hockey injuries in an elite Japanese ice hockey team.

Design:

Prospective observational cohort study design.

Setting:

An elite ice hockey team, Tokyo, Japan.

Patients or Other Participants:

Ninety-four players during the 2002–2005 seasons.

Main Outcome Measure(s):

Data were collected for 3 consecutive seasons using an injury reporting form.

Results:

The overall game injury rate was 74.3 per 1000 player-game hours and 11.7 per 1000 player-game hours for injuries resulting in any time loss. The overall practice injury rates were 11.2 per 1000 player-practice hours and 1.1 per 1000 player-practice hours for injuries resulting in any time loss. Forwards had the highest rate of injury, followed by defensemen and then goalkeepers. Contusions were the most common injury, followed by strains, lacerations, and sprains.

Conclusions:

Most injuries among Japanese ice hockey players occurred during games. Game or play intensity may influence the injury rate during games.     

Two different fatigue protocols and lower extremity motion patterns during a stop-jump task

Context:

Altered neuromuscular control strategies during fatigue probably contribute to the increased incidence of non-contact anterior cruciate ligament injuries in female athletes.

Objective:

To determine biomechanical differences between 2 fatigue protocols (slow linear oxidative fatigue protocol [SLO-FP] and functional agility short-term fatigue protocol [FAST-FP]) when performing a running-stop-jump task.

Design:

Controlled laboratory study.

Setting:

Laboratory.

Patients or Other Participants:

A convenience sample of 15 female soccer players (age = 19.2 ±0.8 years, height = 1.67±0.05m, mass = 61.7 + 8.1 kg) without injury participated.

Intervention(s):

Five successful trials of a running–stop-jump task were obtained prefatigue and postfatigue during the 2 protocols. For the SLO-FP, a peak oxygen consumption (V˙o₂peak) test was conducted before the fatigue protocol. Five minutes after the conclusion of the V˙o₂peak test, participants started the fatigue protocol by performing a 30-minute interval run. The FAST-FP consisted of 4 sets of a functional circuit. Repeated 2 (fatigue protocol) × 2 (time) analyses of variance were conducted to assess differences between the 2 protocols and time (prefatigue, postfatigue).

Main Outcome Measure(s):

Kinematic and kinetic measures of the hip and knee were obtained at different times while participants performed both protocols during prefatigue and postfatigue.

Results:

Internal adduction moment at initial contact (IC) was greater during FAST-FP (0.064 ±0.09 Nm/kgm) than SLO-FP (0.024±0.06 Nm/kgm) (F_1,14 = 5.610, P=.03). At IC, participants had less hip flexion postfatigue (44.7°±8.1°) than prefatigue (50.1°±9.5°) (F_1,14 = 16.229, P=.001). At peak vertical ground reaction force, participants had less hip flexion postfatigue (44.7°±8.4°) than prefatigue (50.4°±10.3°) (F_1,14 = 17.026, P=.001). At peak vertical ground reaction force, participants had less knee flexion postfatigue (−35.9°±6.5°) than prefatigue (−38.8°±5.03°) (F_1,14 = 11.537, P=.001).

Conclusions:

Our results demonstrated a more erect landing posture due to a decrease in hip and knee flexion angles in the postfatigue condition. The changes were similar between protocols; however, the FAST-FP was a clinically applicable 5-minute protocol, whereas the SLO-FP lasted approximately 45 minutes.     

Severe road traffic injuries in Kenya, quality of care and access

Background

Road traffic injuries (RTI) are on increase in developing countries. Health care facilities are poorly equipped to provide the needed services.

Objective

Determine access and quality of care for RTI casualties in Kenya.

Design

Cross-sectional survey

Setting

53 large and medium size private, faith-based and public hospitals.

Participants

In-patient road traffic crash casualties and health personnel in the selected hospitals were interviewed on availability of emergency care and resources. Onsite verification of status was undertaken.

Results

Out of 310 RTI casualties interviewed, 72.3%, 15.6% and 12.2% were in public, faith-based and private hospitals, respectively. Peak age of the injured was 15–49 years. First aid was availed to 16.0% of casualties. Unknown persons transported 76.5% of the injured. Police and ambulance vehicles transported 6.1% and 1.4%, respectively. 51.9% reached health facilities within 30 minutes of crash and medical care provided to 66.2% within one hour. 40.8% of recipient facilities were adequately prepared for RTI emergencies.

Conclusions

Most RTI casualties were young and from poor backgrounds. Training of motorists and general public in first aid should be considered in RTI control initiatives. Availability of basic trauma care medical supplies in public health facilities was highly deficient.     

Sweat Rates, Sweat Sodium Concentrations, and Sodium Losses in 3 Groups of Professional Football Players

Context:

Sweat sodium losses have never been reported in a large cohort of American football players.

Objective:

To compare sweat rates (SwtRs), sweat sodium concentrations (SwtNa⁺), and sodium losses in 3 groups of players (backs and receivers [BK], linebackers and quarterbacks [LB/QB], and linemen [LM]) to determine if positional differences and, therefore, size differences exist.

Design:

Observational study.

Setting:

Data were collected during practices in the second week of 2 consecutive training camps. The wet bulb globe temperature was 78.5°F ± 3.5°F (25.9°C ± 1.9°C).

Patients or Other Participants:

Eighteen BK, 12 LB/QB, and 14 LM volunteered.

Intervention(s):

Sterile sweat patches were applied to the right forearm after the skin was appropriately cleaned. The patches were removed during practice, placed in sterile tubes, centrifuged, frozen, and later analyzed by flame photometry.

Main Outcome Measure(s):

Sweat rate, SwtNa⁺, and sodium loss. We calculated SwtR by change in mass adjusted for urine produced and fluids consumed divided by practice time in hours.

Results:

Other than age, physical characteristics were different among groups (P < .001). The SwtR was different among groups (F_2,41  =  7.3, P  =  .002). It was lower in BK (1.42 ± 0.45 L/h) than in LB/QB (1.98 ± 0.49 L/h) (P < .05) and LM (2.16 ± 0.75 L/h) (P < .01), but we found no differences between SwtRs for LB/QB and LM. The SwtNa⁺ was not different among groups (BK  =  50 ± 16 mEq/L, LB/QB  =  48.2 ± 23 mEq/L, and LM  =  52.8 ± 25 mEq/L) and ranged from 15 to 99 mEq/L. Sweat sodium losses ranged from 642 mg/h to 6.7 g/h, and findings for group comparisons approached significance (P  =  .06). On days when players practiced 4.5 hours, calculated sodium losses ranged from 2.3 to 30 g/d.

Conclusions:

The BK sweated at lower rates than did the midsized LB/QB and large LM, but LB/QB sweated similarly to LM. Sweat sodium concentration and daily sodium losses ranged considerably. Heavy, salty sweaters require increased dietary consumption of sodium during preseason.