Asymmetry in internal oblique muscle thickness: Not the key to a cricket fast bowler's performance

Purpose Previous studies found that trunk muscle asymmetry may play a role in preventing injury in cricket fast bowlers, while the association with bowling performance has not been investigated. This study aims to describe the side-to-side differences in trunk muscle thickness and determine the association between bowling performance and these side-to-side differences in trunk muscle thickness in adolescent fast bowlers. Methods In this observational cross-sectional study, bowling performance, namely ball release speed and bowling accuracy, was recorded in adolescent fast bowlers. Ultrasound imaging measured external oblique, internal oblique, transversus abdominis and lumbar multifidus muscle thickness. Results Fast bowlers (n = 46) with a mean age of 15.9 (±1.2) years participated. On the non-dominant side, the external oblique and internal oblique at rest were thicker than on the dominant side (external oblique: p = 0.011, effect size = 0.27; internal oblique: p < 0.0001, effect size = 0.40), while the transversus abdominus ( p = 0.72, effect size = 0.19) and lumbar multifidus ( p = 0.668, effect size = 0.04) were symmetrical. Weak correlations existed between bowling performance and the side-to-side differences in the thickness in all muscles, except for two moderate correlations: 1. The smaller the side-to-side difference in absolute thickness of the external oblique when contracted, the faster the ball release speed (Spearman's (ρ) = −0.455, p = 0.002). 2. Also, a smaller side-to-side difference in external oblique contraction ratio (Spearman's (ρ) = −0.495, p = 0.0001) was associated with faster ball release speed. Conclusions No relationship between bowling performance and side-to-side differences in internal oblique muscle thickness could be established, while more symmetrical external oblique muscles may be linked to faster ball release speeds.

Exercise Modality Affects Older Adult CT-Derived Muscle and Bone Loss During Caloric Restriction

Caloric restriction (CR) can exacerbate muscle and bone loss. We examined 18-month changes in computed tomography (CT)-derived trunk muscle, and volumetric bone mineral density (vBMD) and finite element-estimated bone strength of the spine and hip in 55 older adults randomized to CR alone or CR plus aerobic (CR+AT) or resistance (CR+RT) training. Trunk muscle area loss trended higher with CR+AT [-16.8 cm2 (95% CI: -26.4,-7.1) vs CR: -6.7 (-12.8,-0.5), CR+RT: -9.0 (-14.5,-3.4)]. Spine vBMD loss trended higher with CR+AT [−0.014 g/cm3 (−0.027,−0.001) vs. CR: −0.005 (−0.022,0.012), CR+RT: −0.004 (−0.019,0.011)], and similarly for vertebral bone strength. Hip vBMD losses trended lower with CR+RT [−0.015 g/cm3 (−0.024,−0.006) vs. CR: −0.027 (−0.036,−0.019), CR+AT: −0.029 (−0.037,−0.020)]. Hip vBMD and trunk muscle losses were positively correlated (r=0.53), and spine vBMD loss tended to increase with trunk muscle loss (r=0.21) and fat infiltration (r=0.17). Collectively, aerobic training was less effective at preserving muscle-bone health during CR.

Trunk Muscle Activation Patterns During Standing Turns in Patients With Stroke: An Electromyographic Analysis

Recent evidence indicates that turning difficulty may correlate with trunk control; however, surface electromyography has not been used to explore trunk muscle activity during turning after stroke. This study investigated trunk muscle activation patterns during standing turns in healthy controls (HCs) and patients with stroke with turning difficulty (TD) and no TD (NTD). The participants with stroke were divided into two groups according to the 180° turning duration and number of steps to determine the presence of TD. The activation patterns of the bilateral external oblique and erector spinae muscles of all the participants were recorded during 90° standing turns. A total of 14 HCs, 14 patients with TD, and 14 patients with NTD were recruited. The duration and number of steps in the turning of the TD group were greater than those of the HCs, independent of the turning direction. However, the NTD group had a significantly longer turning duration than did the HC group only toward the paretic side. Their performance was similar when turning toward the non-paretic side; this result is consistent with electromyographic findings. Both TD and NTD groups demonstrated increased amplitudes of trunk muscles compared with the HC groups. Their trunk muscles failed to maintain consistent amplitudes during the entire movement of standing turns in the direction that they required more time or steps to turn toward (i.e., turning in either direction for the TD group and turning toward the paretic side for the NTD group). Patients with stroke had augmented activation of trunk muscles during turning. When patients with TD turned toward either direction and when patients with NTD turned toward the paretic side, the flexible adaptations and selective actions of trunk muscles observed in the HCs were absent. Such distinct activation patterns during turning may contribute to poor turning performance and elevate the risk of falling. Our findings provide insights into the contribution and importance of trunk muscles during turning and the association with TD after stroke. These findings may help guide the development of more effective rehabilitation therapies that target specific muscles for those with TD.