Fifty-seven athletes were recruited for the study. Eleven of these athletes were excluded as less than three weeks of data were collected over the 15 week period of data collection, due to either absence from training (n = 10) or dropping out of the basketball program (n = 1). If an athlete sustained a limiting injury, their data was only included for analysis if at least three weeks of participation data were collected prior to the injury. Forty-six participants (28 boys and 18 girls, mean age 16.0 years, range 14.7 to 18.1 years) completed the study. No differences in age, years playing basketball or injury rate or type were found between male and female athletes, therefore all athletes were considered as one data group for analysis.

Seven athletes were injured at baseline, however none of these injuries were causing modified participation in physical activity. No significant differences were found in the weekly participation hours undertaken during the season by players injured and not injured at baseline (t (39) = 0.896, p = 0.38).

Physical activity data
The mean (SD) hours of physical activity undertaken by participants was 10.1 (3.3) per week. Basketball was the single activity with the highest weekly participation volume (mean 7.7 hours per week). The mean (SD) hours of weekly participation in all other organised sports (including cricket, Australian Rules football, kickboxing, karate, soccer, netball, softball, tennis and squash) was 0.5 (1.0) hours combined. Other common activities included weight training, physical education class and running (Table 1).

Basketball activity included training (58.5 %), competition (16 %), refereeing (11.6 %), shooting practice (10.1 %) and recreational basketball (3.9 %).

Injury data
Twenty-six athletes (56.5%) sustained 35 injuries. The incidence rate of injuries per athlete over the season was 0.76. Twenty-one athletes suffered a single injury, five athletes suffered two injuries and two athletes sustained three injuries over the season. The season injuries comprised of 62.9% acute and 37.1% overuse injuries. Of the acute injuries, 59.1 % were contact injuries and 40.9% non-contact.

The majority of injuries involved the lower limb (n = 22, 62.9%). Ten were injuries to the hip and thigh, eight involved the knee/shin/calf and four involved the ankle or foot. Injuries to the upper limb accounted for 20% of injuries (n = 7). Of the upper limb injuries, the majority involved the hand or wrist (n = 4), two were to the shoulder or upper arm and one involved the elbow/forearm. The remaining injuries involved the trunk (n = 4, 11.4%) and the head and neck (n = 2, 5.7%).

The nature of injury most commonly reported by the athletes was pain (n = 9, 25.7 %), followed by overuse injury to the muscle or tendon (n = 7, 20%) and muscle strain (n = 7, 20 %). Five of the injuries were characterized as a bruise/contusion (14.3%), four as a ligament sprain (11.4 %), and three as inflammation or swelling (8.6 %).

The majority of injuries suffered during the season were non-limiting injuries (n = 26, 74.3%). Limiting injuries comprised 25.7% of injuries (n = 9). Participation modification ranged from one day to just under a month, and no athletes sustained a season-ending injury. According to the Sports Medicine Australia severity assessment tool, the large majority of injuries sustained during the season were minor injuries (66.7%).

Injured versus uninjured athletes
Athletes were separated into those injured and not injured during the season, and their demographic data were compared. There were no significant differences in age (z = -.598, p = 0.55), sex (χ² (1, N = 46) = 0.51, p > 0.05), height (z = -. 611, p = 0.54), weight (t (44) = -.651, p = 0.52), or years playing basketball (t (44) = -.312, p = 0.76) between injured and uninjured groups.

No significant differences were found in the total amount of physical activity undertaken weekly by injured and uninjured athletes (t (41) = 0. 434, p = 0.67, Table 2). The two groups differed significantly in the hours of refereeing performed each week, with the injured group performing 1.21 hours and the uninjured 0.54 hours (z = -2.096, p = 0.04). Other additional forms of basketball participation including shooting practice (z = -1.711, p = 0.09) and recreational basketball (z = -1.86, p = 0. 06) were also somewhat greater in the injured group.

Uninjured athletes, athletes suffering only acute injuries, and athletes suffering only overuse injuries were compared with respect to weekly participation hours. Athletes who suffered only overuse injuries participated in a greater amount of refereeing than uninjured athletes (z = -2.802, p = 0.01, Table 3). This was not the case in acutely injured athletes (z = -1.6, p = 0. 53). Athletes who suffered only acute injuries participated in a larger weekly volume of shooting practice than uninjured athletes (z = -2.263, p = 0.02) and athletes suffering overuse injuries (z = -2.309, p = 0.02).

This pilot study examined the association between volume and type of physical activity, and injury occurrence in a group of young basketball players. It was found that athletes who sustained an injury over the data collection period did not participate in a significantly different volume of total weekly physical activity when compared to athletes that remained uninjured. Injured athletes however, participated in significantly more basketball refereeing each week than uninjured athletes. There was also a trend for weekly hours of shooting practice and recreational basketball participation to be higher in injured athletes.

This study indicates that additional repetitive and running-type activities may increase the young basketball player's risk of injury. These findings support previous studies which link increased risk of injury to greater running duration (Burns et al., 2003; Vleck and Garbutt, 1998). Refereeing and recreational basketball activities involve large amounts of running as well as changes of direction, which could explain the reason behind their association with injury. Although the actual difference in hours of refereeing was small between the two groups (1.21 hours per week in injured athletes and 0.54 hours in uninjured athletes), the findings highlight the potential impact of supplementary forms of basketball participation (i.e. not training or competition) on injury risk.

Only overuse injuries were significantly related to amount of weekly refereeing. Past studies which have demonstrated a greater incidence of overall injury with increased participation, have attributed this purely to the increased time available for an injury to occur (Egermann et al., 2003). This study, that found only overuse injury associated with weekly refereeing, negates this suggestion.

Acute injury was significantly associated with volume of shooting practice. As the majority of acute injuries were contact injuries (59.1%), it does not appear that the repetitious shooting action itself was the main cause of injury. Rather, shooting practice provided increased exposure time for acute injuries to occur (e.g. finger hit by the ball or a rolled ankle as running forward for the rebound).

Limitations of the study
The accuracy of documented physical activity duration was maximised with prospective data collection and a maximum of one week recall, though self report has inherent error. Self reporting is however an extremely cost efficient, and practical method of collecting large amounts of data (Sallis et al., 1993).

As this study focused on participation duration and type, intensity was not measured directly. However the categorisation of basketball participation into training, competition, and additional basketball activities did measure the intensity of participation somewhat. As intensity may plausibly impact on injury risk, significant relationships may not have been detected due to that missing parameter of participation. Only a small number of past studies have measured the intensity of participation in addition to duration, and compared this data to injury occurrence (Anderson et al., 2003; Gabbett, 2004; Quarrie et al., 2001). This is most likely due to difficulties in gathering accurate and consistent estimations of intensity (Dennis et al., 2003).

• Basketball players participating in larger amounts of running-type physical activity, in addition to regular training and competition, may be predisposed to overuse injury
• Future studies using larger sample sizes are required to investigate the precise volumes of physical activity that increase injury risk
• This would assist in the development of participation guidelines to decrease the current injury rates observed in the young athletic population.