Sam Oxford

The Effect of Caffeine Ingestion on Mood State and Bench Press Performance to Failure

Duncan, MJ and Oxford, SW. The effect of caffeine ingestion on mood state and bench press performance to failure. J Strength Cond Res 25(1): 178-185, 2011-Research has suggested that caffeine enhances aerobic performance. The evidence for high-intensity, short-term exercise, particularly resistance exercise is mixed and has not fully examined the psychological changes that occur after this mode of exercise with caffeine ingestion. This study examined the effect of caffeine (5 mg·kg−1) vs. placebo on bench press exercise to failure and the mood state response pre to postexercise. Thirteen moderately trained men (22.7 ± 6.0 years) completed 2 laboratory visits, after determination of 1 repetition maximum (1RM) on the bench press, where they performed bench press repetitions to failure at a load of 60% 1RM. Mood state was assessed 60 minutes pre and immediately post-substance ingestion. Borgs rating of perceived exertion (RPE) and peak blood lactate (PBla) were assessed after each test, and peak heart rate (PHR) was determined using heart rate telemetry. Participants completed significantly more repetitions to failure (p = 0.031) and lifted significantly greater weight (p = 0.027) in the caffeine condition compared to the placebo condition. The PHR (p = 0.0001) and PBla (p = 0.002) were higher after caffeine ingestion. The RPE was not different across conditions (p = 0.082). Mood state scores for vigor were greater (p = 0.001) and fatigue scores lower (p = 0.04) in the presence of caffeine. Fatigue scores were greater postexercise (p = 0.001) compared to scores pre exercise across conditions. Caffeine ingestion enhances performance in short-term, resistance exercise to failure and may favorably change the mood state response to exercise compared to a placebo.

The Effect of Exercise Intensity on Postresistance Exercise Hypotension in Trained Men

Abstract Duncan, MJ, Birch, SL, and Oxford, SW. The effect of exercise intensity on postresistance exercise hypotension in trained men. J Strength Cond Res 28(6): 1706–1713, 2014—The occurrence of postresistance exercise hypotension (PEH) after resistance exercise remains unknown. This study examined blood pressure and heart rate (HR) responses to an acute bout of low- and high-intensity resistance exercise, matched for total work, in trained males. Sixteen resistance-trained males (23.1 ± 5.9 years) performed an acute bout of low- (40% of 1 repetition maximum [1RM]) and high-intensity resistance exercise (80% 1RM), matched for total work, separated by 7 days and performed in a counterbalanced order. Systolic blood pressure (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), and HR were assessed before exercise, after completion of each exercise resistance exercise (3 sets of back squat, bench press, and deadlift) and every 10 minutes after resistance exercise for a period of 60 minutes. Results indicated a significant intensity × time interaction for SBP (p = 0.034, partial &eegr;2 = 0.122) and MAP (p = 0.047, partial &eegr;2 = 0.116) whereby SBP and MAP at 50-minute recovery and 60-minute recovery were significantly lower after high-intensity exercise (p = 0.01 for SBP and p = 0.05 for MAP in both cases) compared with low-intensity exercise. There were no significant main effects or interactions in regard to DBP (all p > 0.05). Heart rate data indicated a significant main effect for time (F(9, 135) = 2.479, p = 0.0001, partial &eegr;2 = 0.344). Post hoc multiple comparisons indicated that HR was significantly higher after squat, bench press, and deadlift exercise compared with resting HR and HR at 40-, 50-, and 60-minute recovery (all p = 0.03). The present findings suggest that an acute bout of high intensity, but not low intensity, resistance exercise using compound movements can promote PEH in trained men.

Examining Relative Age Effects in Fundamental Skill Proficiency in British Children Aged 6-11 Years.

Abstract Birch, S, Cummings, L, Oxford, SW, and Duncan, MJ. Examining relative age effects in fundamental skill proficiency in British children aged 6–11 years. J Strength Cond Res 30(10): 2809–2815, 2016—The relative age effect (RAE) suggests that there is a clustering of birth dates just after the cutoff used for sports selection in age-grouped sports and that in such circumstances, relatively older sportspeople may enjoy maturational and physical advantages over their younger peers. Few studies have examined this issue in nonselective groups of children, and none have examined whether there is evidence of any RAE in skill performance. The aim of this study was to assess whether there were differences in fundamental movement skill (FMS) proficiency within children placed in age groups according to the school year. Six FMS (sprint, side gallop, balance, jump, catch, and throw) were assessed in 539 school children (258 boys and 281 girls) aged 6–11 years (mean age ± SD = 7.7 ± 1.7 years). We examined differences in these FMS between gender groups and children born in different quarters of the year after controlling for age and body mass index (BMI). For balance, chronological age was significant as a covariate (p = 0.0001) with increases in age associated with increases in balance. Boys had significantly higher sprint mastery compared with girls (p = 0.012), and increased BMI was associated with poorer sprint mastery (p = 0.001). Boys had higher catching mastery than girls (p = 0.003), and children born in Q1 had significantly greater catching mastery than those born in Q2 (p = 0.015), Q3 (p = 0.019), and Q4 (p = 0.01). Results for throwing mastery also indicated higher mastery in boys compared with girls (p = 0.013) and that children born in Q1 had higher throwing proficiency than those born in Q4 (p = 0.038). These results are important if coaches are basing sport selection on measures of skilled performance, particularly in object-control skills. Categorizing childrens skilled performance based on rounded down values of whole-year age may disadvantage children born relatively later in the selection year, whereas children born earlier in the selection year will likely evidence greater skill mastery and subsequent advantage for selection purposes.

The effects of arm crank ergometry, cycle ergometry and treadmill walking on postural sway in healthy older females

Older adults are increasingly being encouraged to exercise but this may lead to muscle fatigue, which can adversely affect postural stability. Few studies have investigated the effects of upper body exercise on postural sway in groups at risk of falling, such as the elderly. The purpose of this study was to compare the effects arm crank ergometry (ACE), cycle ergometry (CE) and treadmill walking (TM) on postural sway in healthy older females. In addition, this study sought to determine the time necessary to recover postural control after exercise. A total of nine healthy older females participated in this study. Participants stood on a force platform to assess postural sway which was measured by displacement of the centre of pressure before and after six separate exercise trials. Each participant completed three incremental exercise tests to 85% of individuals theoretical maximal heart rate (HRMAX) for ACE, CE and TM. Subsequent tests involved 20-min of ACE, CE and TM exercise at a relative workload corresponding to 50% of each individuals predetermined heart rate reserve (HRE). Post fatigue effects and postural control recovery were measured at different times after exercise (1, 3, 5, 10, 15 and 30-min). None of the participants exhibited impaired postural stability after ACE. In contrast, CE and TM elicited significant post exercise balance impairments, which lasted for ∼ 10 min post exercise. We provide evidence of an exercise mode which does not elicit post exercise balance impairments. Older adults should exercise caution immediately following exercise engaging the lower limbs to avoid fall risk.

The effects of 10 weeks Integrated Neuromuscular Training on fundamental movement skills and physical self-efficacy in 6-7 year old children

Abstract Duncan, MJ, Eyre, ELJ, and Oxford, SW. The effects of 10-week integrated neuromuscular training on fundamental movement skills and physical self-efficacy in 6–7-year-old children. J Strength Cond Res 32(12): 3348–3356, 2018—Integrated neuromuscular training (INT) has been suggested as an effective means to enhance athletic potential in children. However, few studies have reported the effects of school-based INT programs. This study examined the effect of INT on process and product fundamental movement skill measures and physical self-efficacy in 6–7-year-old children. Ninety-four children from 2 primary schools were randomized into either a 10-week INT program or a control group (CON) (n = 41). Results indicated significantly greater increases in process fundamental movement skill (FMS) scores in INT vs. CON (p = 0.001). For product measures of FMS, 10-m sprint time, counter movement jump, seated medicine ball throw and standing long jump (all p = 0.001), all significantly increased to a greater extent in the INT group vs. CON. A significant group (INT vs. CON) × time (pre vs. post) × gender interaction for physical self-efficacy revealed increased physical self-efficacy pre to post INT, compared with CON but only for boys (p = 0.001). For girls, physical self-efficacy was not significantly different before to after the 10-week period for INT and CON groups. The results of this study suggest that replacing 1 of the 2 weekly statutory physical education (PE) lessons with an INT program over a 10-week period results in positive improvements in fundamental movement skill quality and outcomes in 6–7-year-old children. Integrated neuromuscular training also appears to increase physical self-esteem to a greater extent than statutory PE but only in boys.

Coffee and Caffeine Ingestion Have Little Effect on Repeated Sprint Cycling in Relatively Untrained Males

The present study investigated the effect of ingesting caffeine-dose-matched anhydrous caffeine or coffee on the performance of repeated sprints. Twelve recreationally active males (mean ± SD age: 22 ± 2 years, height: 1.78 ± 0.07 m, body mass: 81 ± 16 kg) completed eighteen 4 s sprints with 116 s recovery on a cycle ergometer on four separate occasions in a double-blind, randomised, counterbalanced crossover design. Participants ingested either 3 mg·kg−1 of caffeine (CAF), 0.09 g·kg−1 coffee, which provided 3 mg·kg−1 of caffeine (COF), a taste-matched placebo beverage (PLA), or a control condition (CON) 45 min prior to commencing the exercise protocol. Peak and mean power output and rating of perceived exertion (RPE) were recorded for each sprint. There were no significant differences in peak power output (CAF: 949 ± 199 W, COF: 949 ± 174 W, PLA: 971 ± 149 W and CON: 975 ± 170 W; p = 0.872; ηP2 = 0.02) or mean power output (CAF: 873 ± 172 W, COF: 862 ± 44 W, PLA: 887 ± 119 W and CON: 892 ± 143 W; p = 0.819; ηP2 = 0.03) between experimental conditions. Mean RPE was similar for all trials (CAF: 11 ± 2, COF: 11 ± 2, PLA: 11 ± 2 and CON: 11 ± 2; p = 0.927; ηP2 = 0.01). Neither the ingestion of COF or CAF improved repeated sprint cycling performance in relatively untrained males.

Optimal Body Size and Limb Length Ratios Associated with 100-m Personal-Best Swim Speeds.

PURPOSE This study aims to identify optimal body size and limb segment length ratios associated with 100-m personal-best (PB) swim speeds in children and adolescents. METHODS Fifty national-standard youth swimmers (21 males and 29 females age 11-16 yr; mean ± SD age, 13.5 ± 1.5 yr) participated in the study. Anthropometry comprised stature; body mass; skinfolds; maturity offset; upper arm, lower arm, and hand lengths; and upper leg, lower leg, and foot lengths. Swimming performance was taken as the PB time recorded in competition for the 100-m freestyle swim. To identify the optimal body size and body composition components associated with 100-m PB swim speeds (having controlled for age and maturity offset), we adopted a multiplicative allometric log-linear regression model, which was refined using backward elimination. RESULTS Lean body mass was the singularly most important whole-body characteristic. Stature and body mass did not contribute to the model, suggesting that the advantage of longer levers was limb-specific rather than a general whole-body advantage. The allometric model also identified that having greater limb segment length ratios [i.e., arm ratio = (low arm)/(upper arm); foot-to-leg ratio = (foot)/(lower leg)] was key to PB swim speeds. CONCLUSIONS It is only by adopting multiplicative allometric models that the above mentioned ratios could have been derived. The advantage of having a greater lower arm is clear; however, having a shorter upper arm (achieved by adopting a closer elbow angle technique or by possessing a naturally endowed shorter upper arm), at the same time, is a new insight into swimming performance. A greater foot-to-lower-leg ratio suggests that a combination of larger feet and shorter lower leg length may also benefit PB swim speeds.

Changes in kinematics and arm–leg coordination during a 100-m breaststroke swim

ABSTRACT The purpose of this study was to compare arm–leg coordination and kinematics during 100 m breaststroke in 26 (8 female; 18 male) specialist breaststroke swimmers. Laps were recorded using three 50-Hz underwater cameras. Heart rate and blood lactate were measured pre- and post-swim. Arm–leg coordination was defined using coordination phases describing continuity between recovery and propulsive phases of upper and lower limbs: coordination phase 1 (time between end of leg kick and start of the arm pull phases); and coordination phase 2 (time between end of arm pull and start of leg kick phases). Duration of stroke phases, coordination phases, swim velocity, stroke length (SL), stroke rate (SR) and stroke index (SI) were analysed during the last three strokes of each lap that were unaffected by turning or finishing. Significant changes in velocity, SI and SL (P < 0.05) were found between laps. Both sexes showed significant increase (P < 0.05) in heart rate and blood lactate pre- to post-swim. Males had significantly (P < 0.01) faster swim velocities resulting from longer SLs (P = 0.016) with no difference in SR (P = 0.064). Sex differences in kinematic parameters can be explained by anthropometric differences providing males with increased propelling efficiency.