Back injuries and the fast bowler in cricket

Here, I review research that has investigated the aetiology of injuries experienced by adolescent and adult fast bowlers. Mechanical factors play an important role in the aetiology of degenerative processes and injuries to the lumbar spine. This is particularly so in fast bowling, where a player must absorb vertical and horizontal components of the ground reaction force that are approximately five and two times body weight at front-foot and rear-foot impact, respectively. Attenuated forces are transmitted to the spine through the lower limb, while additional foces at the lumbo-sacral junction are caused by trunk hyperextension, lateral flexion and twisting during the delivery stride. Fast bowlers are classified as side-on, front-on or mixed. The mixed action is categorized by the lower body configuration of the front-on action and the upper body configuration of the side-on technique. This upper body configuration is produced by counter-rotation away from the batsman in the transverse plane about the longitudinal axis of the body of a line through the two shoulders. Counter-rotations of 12–40° during a delivery stride have predicted an increased incidence of lumbar spondylolysis, disc abnormality and muscle injury in fast bowlers. During the delivery stride, the mixed bowling action also shows: more lateral flexion and hyperextension of the lumbar spine at front-foot impact, and a greater range of motion of the trunk over the delivery stride when compared with the side-on and front-on techniques. The pars interarticularis of each vertebra is vulnerable to injury if repetitive flexion, rotation and hyperextension are present in the activity. Fast bowlers should reduce shoulder counter-rotation during the delivery stride to reduce the incidence of back injuries. When a player is required to bowl for extended periods irrespective of technique, overuse is also related to an increased incidence of back injuries and must be avoided.     

Spot Reduction of Subcutaneous Adipose Tissue

Abstract

This study was designed to determine if the skinfold measurements on an exercised arm would decrease as a result of regular weight training with that arm. Thirty-two subjects completed three sets of 7-RM curls and three sets of 7-RM triceps extensions on either a daily or an alternate day schedule for a period of 6 weeks. The nonexercised arm was measured to establish the specificity of the spot reduction on the exercised arm. The results indicate that hard exercise in a specific area of the arm will result in a reduction of the subcutaneous adipose tissue in that area.     

Lumbo-pelvic loading during fast bowling in adolescent cricketers: The influence of bowling speed and technique

Abstract

This study aimed to assess changes in bowling technique and lumbar load over the course of a bowling spell in adolescent fast bowlers, and to investigate the relationship between lumbar loads during fast bowling and kinematic factors which have previously been associated with low back injury. Three-dimensional motion analysis was carried out on forty participants who performed an 8-over bowling spell. There were no significant changes in bowling technique or lumbar loads over the course of the spell. Bowling with a more extended front knee, faster ball release speed and increased shoulder counter-rotation were related to increased lumbo-pelvic loading – in particular peak transverse plane rotation moments and anterior-posterior shear forces. These lumbar loads may be a factor in low back injury aetiology and future studies should investigate the relationship between lumbar loading, injury incidence and other risk factors.     

An investigation of a novel three-dimensional activity monitor to predict free-living energy expenditure

Abstract

The aim of this study was to assess the capability of the 3dNX? accelerometer to predict energy expenditure in two separate, free-living cohorts. Twenty-three adolescents and 14 young adults took a single dose of doubly labelled water and wore a 3dNX? activity monitor during waking hours for a 10-day period while carrying out their normal routines. Multiple linear regression with backward elimination was used to establish the strength of the associations between various indices of energy expenditure, physical activity counts, and anthropometric variables. 3dNX? output accounted for 27% and 35% of the variance in the total energy expenditure of the adolescent and young adult cohort, respectively. The explained variance increased to 78%, with a standard error of estimate of 7%, when 3dNX? output was combined with body composition variables. The 3dNX? accelerometer can be used to predict free-living daily energy expenditure with a standard error of estimate of 1.65 MJ in adolescents and 1.52 MJ in young adults. The inclusion of anthropometric variables reduces the error to approximately 1 MJ. Although it remains to cross-validate these models in other populations, early indications suggest that the 3dNX? provides a useful method of predicting energy expenditure in free-living individuals.     

Laboratory versus field testing in cricket bowling: A review of current and past practice in modelling techniques

In cricket bowling, the reconstruction of elbow angle data is of utmost importance to the bowling versus throwing argument. This paper reviews system and modelling errors inherent in three-dimensional reconstruction processes with respect to the elbow extension tolerance set by the International Cricket Council. An understanding of these factors will enable more informed decisions about the choice of in-field versus laboratory testing in the calculation of elbow extension during bowling in cricket. Although there is a paucity of objective data related to in-field and laboratory testing, biomechanists must be guided by the greater accuracy of opto-reflective than video-based systems and so testing, at least for the present, should be conducted in a laboratory setting.     

Tennis

The study investigated differences in the one‐ (SH) and two‐handed (DH) backhands when hit flat, across‐court (AC) and down‐the‐line (DL), and with heavy topspin DL (TDL). The ability to disguise each of these backhands when hitting the above strokes was also assessed. Eighteen college‐level male tennis players, identified as having a high performance topspin SH (n = 6) or DH (n = 12) backhand drive, participated in the study. Players were required to hit three AC, DL and TDL backhands from the baseline with their preferred technique, while being filmed with two high‐speed video cameras operating at 200 Hz. The highest horizontal velocity backhand for each stroke was analysed. Results indicated that the sequential coordination of five body segments (hips, shoulder, upper arm, forearm, and hand/racquet rotations) was required for the execution of the SH stroke. The same number of segments were generally coordinated in the DH stroke (hips, shoulders, and varying degrees of upper arm and forearm rotations followed by hand/racquet movement). Mature players produced comparable racquet horizontal velocities 0.005 s prior to impact using either the SH or DH backhand technique. The SH backhand was characterised by a more rotated shoulder alignment than the DH stroke (SH: 119.1°; DH: 83.4°) at the completion of the backswing. At impact the ball was impacted further in front (SH: 0.59 m; DH: 0.40 m) and a similar distance to the side of the body (SH: 0.75 m; DH: 0.70 m). Players using the DH backhand technique delayed the horizontal acceleration of the racquet towards the ball (SH: 0.13 s; DH: 0.08 s prior to impact) and thus were capable of displaying a similar hitting motion closer to impact than players with a SH technique.