The velocity and acceleration at which the ball-carrier or tackler enters the tackle may contribute to winning the contest and prevailing injury free. Velocity and acceleration have been quantified in controlled settings, whereas in match-play it has been subjectively described. The purpose of this study was to determine the velocity and acceleration of the ball-carrier and tackler before contact during match-play in three competitions (Super 14, Varsity Cup, and Under-19 Currie Cup). Using a two-dimensional scaled version of the field, the velocity and acceleration of the ball-carrier and tackler were measured at every 0.1 s to contact for 0.5 s. For front-on tackles, a significant difference (P < 0.05) between the ball-carrier (4.6 ± 1 m · s⁻¹) and tackler (7.1 ± 3.5 m · s⁻¹) was found at the 0.5 s time to contact interval in the Varsity Cup. For side-on tackles, differences between the two opposing players were found at 0.5 s (ball-carrier: 4.6 ± 1.7 m · s⁻¹; tackler: 3.1 ± 1.2 m · s⁻¹) and 0.4 s (ball-carrier: 6.3 ± 2.3 m · s⁻¹; tackler: 3.7 ± 1.6 m · s⁻¹) at Under-19 level. After 0.4 s, no significant differences (P > 0.05) were evident. Also, the ball-carrier's velocity over the 0.5 s was relatively stable compared with that of the tackler. Results suggest that tacklers adjust their velocity to reach a suitable relative velocity before making contact with the ball-carrier.

BackgroundPrevious research has shown that the built environment plays a role in habitual levels of physical activity (PA), however much of this research has been conducted in adults and higher income countries. The aim of this pilot study was to examine the strength of association between the built environment and PA in South African older adults.MethodsParticipants were recruited (n = 44, mean age 65 ± 8.5 years) from two suburbs, representing either a high socioeconomic (HSA) or low socioeconomic area (LSA). Self-reported PA, and subjective assessments of neighborhood walkability (Neighborhood Environment Walkability Scale, NEWS) was measured. Participants wore Actigraph GT3x accelerometers to objectively quantify PA.ResultsHSA participants reported significantly more leisure-time and less transport PA. Objectively measured and self-reported MVPA was significantly higher in HSA participants. NEWS ‘Land-use Mix’ was negatively associated with leisure-time MVPA, (r2 = 0.20; p < 0.02). In addition, neighborhood aesthetics was positively associated with leisure-time physical activity (r2 = 0.33; p = 0.02). ‘Safety from traffic’ was inversely associated with travel-related PA (r2 = 0.14, p = 0.01). None of the other NEWS scores were associated with PA for the total group.ConclusionLeisure-time and transport-related PA was influenced by socio-economic status. Attributes of the perceived built environment associated with leisure-time and total MVPA in older South Africa adults were different in low- and high- income settings.

This pilot study examines the effect of heart rate variability (HRV) biofeedback on measures of electroencephalogram (EEG) during and immediately after biofeedback. Eighteen healthy males exposed to work-related stress, were randomised into an HRV biofeedback (BIO) or a comparative group (COM). EEG was recorded during the intervention and during rest periods before and after the intervention. Power spectral density in theta, alpha and beta frequency bands and theta/beta ratios were calculated. During the intervention, the BIO group had higher relative theta power [Fz and Pz (p < 0.01), Cz (p < 0.05)], lower fronto-central relative beta power (p < 0.05), and higher theta/beta [Fz and Cz (p < 0.01), Pz (p < 0.05)] than the COM group. The groups showed different responses after the intervention with increased posterior theta/beta (p < 0.05) in the BIO group and altered posterior relative theta (p < 0.05), central relative beta (p = 0.06) and central-posterior theta/beta (p < 0.01) in the post-intervention rest period. The findings of this study suggest that a single session of HRV biofeedback after a single training session was associated with changes in EEG suggestive of increased internal attention and relaxation both during and after the intervention. However, the comparative intervention was associated with changes suggestive of increased mental effort and possible anxiety during and after the intervention.