Accumulating short bouts of running reduces resting blood pressure in young normotensive/pre-hypertensive men

Abstract

In this study, we compared the effects of accumulated and continuous running on resting arterial blood pressure. Ten normotensive/pre-hypertensive men, aged 25.0 ± 4.2 years (mean ± s), participated in three 2-day trials at least one week apart in a randomized, repeated-measures design. On Day 1, participants rested (control) or ran at 70% of maximum oxygen uptake in either ten 3-min bouts (30 min rest between bouts) or one continuous 30-min bout. On Day 2, participants rested throughout the day. Blood pressure was measured at hourly intervals throughout Days 1 and 2. Mean resting systolic blood pressure on Day 2 was 6% lower during the accumulated and continuous running trials compared with the control trial (110 ± 6 vs. 110 ± 8 vs. 117 ± 6 mmHg respectively; P < 0.05), but there were no differences in resting diastolic blood pressure among the three trials (70 ± 7 vs. 69 ± 6 vs. 70 ± 5 mmHg respectively). These findings demonstrate that accumulating 30 min of running throughout the day in short bouts is as effective as 30 min of continuous running for reducing resting systolic blood pressure on the next day in young normotensive/pre-hyptertensive men.     

Ventilatory Threshold,Running Economy and Distance Running Performance of Trained Athletes

Abstract

The purpose of this study was to assess the relationships among ventilatory threshold T(vent), running economy and distance running performance in a group (N=9) of trained experienced male runners with comparable maximum oxygen uptake ([Vdot]O₂ max). Maximal oxygen uptake and submaximal steady state oxygen uptake were measured using open circuit spirometry during treadmill exercise. Ventilatory threshold was determined during graded treadmill exercise using non-invasive techniques, while distance running performance was assessed by the best finish time in two 10-kilometer (km) road races. The subjects averaged 33.8 minutes on the 10km runs, 68.6 ml · kg ^-1 · min ^-1 for [Vdot]O₂ max, and 48.1 ml · kg ^-1 · min ^-1 for steady state [Vdot]O₂ running at 243 meters · min ^-1. The T(vent) (first deviation from linearity of [Vdot]_E, [Vdot]CO ₂ ) occurred at an oxygen consumption of 41.9 ml · kg ^-1 · min ^-1. The relationship between running economy and performance was r = .51 (p>0.15) and the relationship between T(vent) and performance was r = .94 (p < 0.001). Applying stepwise multiple linear regression, the multiple R did not increase significantly with the addition of variables to the T(vent); however, the combination of [Vdot]O₂ max, running economy and T(vent) was determined to account for the greatest amount of total variance (89%). These data suggest that among trained and experienced runners with similar [Vdot]O₂ max, T(vent) can account for a large portion of the variance in performance during a 10km race.     

Influence of Emotion on the Control of Low-Level Force Production

The accuracy and variability of a sustained low-level force contraction (2% of maximum voluntary contraction) was measured while participants viewed unpleasant, pleasant, and neutral images during a feedback occluded force control task. Exposure to pleasant and unpleasant images led to a relative increase in force production but did not alter the variability of force production compared to conditions in which participants viewed neutral images. Findings are discussed with respect to prior work, emphasizing arousal specific changes that emerge at low target force levels.     

Self-Confidence as a Mediator of the Relationship Between Competitive Anxiety Intensity and Interpretation

The aim of this study was to examine whether self-confidence mediated the relationship between competitive anxiety intensity and direction. Elite (n = 102) and nonelite (n = 144) participants completed the self-confidence subscale of the Competitive Trait Anxiety Inventory-2 and the worry and somatic subscales from the Sport Anxiety Scale. Consistent with procedures recommended by Baron and Kenny (1986), linear regression analyses were used. The findings for elite athletes revealed worry intensity to significantly predict self-confidence and worry direction. However, when self-confidence was controlled, worry intensity did not predict worry direction over that which was significantly predicted by self-confidence. Within the analysis for somatic symptoms, only self-confidence was found to predict somatic symptom direction. For the nonelite athletes, worry and somatic symptom intensity predicted both self-confidence and direction, and direction when self-confidence was controlled. The findings for the elite athletes suggest self-confidence mediates the relationship between performers' worry symptoms and subsequent directional interpretations. However, the findings suggest that high levels of self-confidence and low symptom intensity are needed for nonelite athletes to demonstrate a less debilitative interpretation.     

Effect of a concentric warm-up exercise on eccentrically induced soreness and loss of function of the elbow flexor muscles

Abstract

The aim of this study was to examine the effect of concentric warm-up exercise on eccentrically induced changes in muscle strength, range of motion, and soreness of the elbow flexors. Ten resistance-exercise naïve participants performed intermittent incremental eccentric actions (42 in total) of the elbow flexor muscles of each arm to induce muscle damage. The arms of each participant were randomly assigned either to a pre-eccentric exercise warm-up involving intermittent concentric exercise (warm-up) or no prior exercise (control). Strength, range of motion, and ratings of soreness were recorded before and 1, 2, 3, 4, and 7 days after exercise. Strength, range of motion, and soreness during muscular movements changed over time (P at most 0.01; Cohen's d at least 0.51, medium). There was an interaction (P < 0.001) for strength, showing a smaller reduction after exercise for warm-up than control (P < 0.001, d = 2.44, large effect). The decreased range of motion was less for warm-up than control for the arm while extended (P < 0.001), flexed (P = 0.002), and relaxed (P = 0.004). Muscle soreness was reduced for the warm-up group, while the muscle was flexed, extended, and relaxed compared with control (P < 0.001). The results demonstrate that a concentric warm-up exercise attenuates the reduction in loss of strength, range of motion, and muscle soreness after eccentric-exercise-induced muscle damage and might allow higher intensities of training to be performed.     

Effects of Altered Stride Lengths on Ratings of Perceived Exertion during Running

Abstract

The purpose of this study was to determine the effects of stride length variations on ratings of perceived exertion (RPEs) in experienced recreational runners. Twenty-eight male college students were randomly divided into equal-sized treatment and control groups. The treatment group performed five 15 min altered stride length runs, each separated by a minimum of 48 hr. The five trials involved running with a freely chosen stride length (FCSL) and a FCSL altered by +14%, +7%, ?14%, and ?7%. The control group was utilized to monitor changes in subjects' RPEs as a result of practice effects developed through repeated bouts of treadmill running. Results revealed that the treatment group's local and general RPEs for the over striding runs (+14%, +7%) were significantly greater (p < .01) than RPEs recorded during the FCSL run. Additionally, there was a marginally significant difference (p < .05) in local RPEs between the FCSL run and the extreme understriding run (?14%). Analysis of variance on the control group's RPE data suggests that neither local nor general RPEs changed significantly in repeated FCSL runs across the six-week testing period. The results of this study suggest that experienced recreational runners perceive differences in exertion accompanying changes in stride length.     

The Mechanics of Batting: Analysis of Ground Reaction Forces and Selected Lower Extremity Kinematics

Abstract

The purpose of this study was to examine variations in ground reaction forces and selected lower extremity kinematics during the stride and swing phases of batting. High speed photography (100 fps) employing direct linear transformation methodology and a force plate were used to record three-dimensional kinematic and kinetic data for 7 female fast pitch softball batters. Mean vertical forces (F_z) of the right or rear foot increased to approximately 1 BW during the stride. Once the left or forward foot made contact with the ground after completion of the stride, right F_z forces decreased to .43 BW while left F_z forces rapidly increased to 1.6 BW at contact. The mean decrease in right F_z forces from peak force until contact was 55%, and the ratio of left to right F_z forces; at impact was 3.67:1. Right mediolateral forces (F_x) were exerted laterally, away from the batter, and were responsible for initiating movement of the body toward the pitched ball. As the left foot made contact with the ground at completion of the stride, left F_x forces were exerted laterally toward the pitched ball. The reaction to these forces retarded the batter's forward momentum, increased stability, and caused the left hip and knee to extend as contact approached. Right and left anteroposterior forces (F_y) acted in opposite directions (right foot pushing backward, left foot pushing forward), and were responsible for rotating the hips and upper body in a counterclockwise direction toward the pitched ball. Horizontal angular deceleration of both thighs just prior to contact was due, in part, to a decrease in these forces. These data may prove helpful when attempting to identify atypical batting patterns, and when considering improvements in shoe design. In the latter instance, force production and stability may be enhanced by aligning the cleats along the lines of action of the applied resultant shear forces.     

A Prelongitudinal Test of Motor Stage Theory

Abstract

A test of motor stage theory was conducted to screen cross-sectionally for the existence of “horizontal structure” among motor sequences within four movement components of overarm throwing and overarm striking for force. A total of 58 male subjects were filmed performing five trials of each task. Comparisons were made between movement component sequence levels as assessed by Roberton's Component Category Checklist for the Overarm Throw and Langendorfer's Component Category Checklist for Overarm Striking. Results indicated that longitudinal study of sequences within the components of trunk, humerus, forearm-racquet actions was warranted and that intertask comparisons of motor sequences were best represented by combinations of stage models proposed by Wohlwill (1973). The observed movement commonalities in the present data were consistent with constructs in both Piagetian developmental stage theory and Schmidt's schema theory in motor control and learning.     

Cricket fast bowling performance and technique and the influence of selected physical factors during an 8-over spell

The aims of this study were to determine the influence of an 8-over spell on cricket fast bowling technique and performance (speed and accuracy), and to establish the relationship of selected physical capacities with technique and performance during an 8-over spell. Fourteen first-grade fast bowlers with a mean age of 23 years participated in the study. Physical capacities assessed were abdominal strength, trunk stability, selected girth and skinfold measures. During the delivery stride, bowlers were filmed from an overhead and lateral perspective (50 Hz) to obtain two-dimensional data for transverse plane shoulder alignment and sagittal plane knee joint angle respectively. Ball speed was measured by a radar gun and accuracy by the impact point of each delivery on a zoned scoring target at the batter's stumps. Shoulder counter-rotation did not change significantly between overs 2 and 8 for all bowlers, but was significantly related to a more front-on shoulder orientation at back foot impact. When the front-on fast bowlers ( n = 5) were isolated for analysis, shoulder counter-rotation increased significantly between overs 2 and 8. Ball speed remained constant while accuracy showed some non-significant variation during the spell. Shoulder counter-rotation was significantly related to accuracy scores during the second half of the 8-over spell. Chest girth and composition and body composition were significantly related to ball release speed at various times during the spell.