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Michael J. Duncan

A 10-week plyometrics-based intervention was carried out with a county-level hurler during preseason preparation. The intervention resulted in a number of physiological changes specific to hurling performance. Most notably, it enabled the athlete to complete repeated sprints with less decrement in performance compared with baseline scores.

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Neil D. Clarke and Michael J. Duncan

Purpose:

To investigate the effect of ingesting carbohydrate and caffeine solutions on measures that are central to success in badminton.

Methods:

Twelve male badminton players performed a badminton serve-accuracy test, coincidence-anticipation timing (CAT), and a choice reaction-time sprint test 60 min before exercise. Participants then consumed 7 mL/kg body mass of either water (PLA), 6.4% carbohydrate solution (CHO), a solution containing a caffeine dose of 4 mg/kg, or 6.4% carbohydrate and 4 mg/kg caffeine (C+C). All solutions were flavored with orange-flavored concentrate. During the 33-min fatigue protocol, participants were provided with an additional 3 mL/kg body mass of solution, which was ingested before the end of the protocol. As soon as the 33-min fatigue protocol was completed, all measures were recorded again.

Results:

Short-serve accuracy was improved after the ingestion of CHO and C+C compared with PLA (P = .001, ηp 2 = .50). Long-serve accuracy was improved after the ingestion of C+C compared with PLA (P < .001, ηp 2 = .53). Absolute error in CAT demonstrated smaller deteriorations after the ingestion of C+C compared with PLA (P < .05; slow, ηp 2 = .41; fast, ηp 2 = .31). Choice reaction time improved in all trials with the exception of PLA, which demonstrated a reduction (P < .001, ηp 2 = .85), although C+C was faster than all trials (P < .001, ηp 2 = .76).

Conclusion:

These findings suggest that the ingestion of a caffeinated carbohydrate solution before and during a badminton match can maintain serve accuracy, anticipation timing, and sprinting actions around the court.

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Michael J. Duncan, Mark Lyons and Joanne Hankey

Purpose:

This study examined the placebo effect of caffeine on number of repetitions (reps), rating of perceived exertion (RPE), blood pressure (BP), and peak heart rate (PHR) during resistance-training exercise with repetitions (reps) performed to volitional failure.

Methods:

Following determination of 1-rep maximum in single-leg leg extension, 15 males performed reps to failure at 60% 1-RM in 3 conditions: control, perceived caffeine condition, and perceived placebo condition presented in a randomized order. Participants were informed they would ingest 250 mL of solution that contained either 3 mg·kg−1 caffeine or 3 mg·kg−1 placebo 1 h before each exercise trial. A deceptive protocol was employed and subjects consumed a placebo solution in both conditions. During each condition, total reps, RPE for the active muscle and overall body, and PHR were recorded.

Results:

Subjects completed 2 more reps when they perceived they had ingested caffeine. RPE was significantly (P = .04) lower in the perceived caffeine and control conditions and RPE for the active muscle was significantly higher across all conditions compared with RPE for the overall body. No substantial differences were evident in PHR across conditions.

Conclusions:

Results of this study are similar to studies of actual caffeine ingestion. However, the perception of consuming a substance that purportedly enhances performance is sufficient enough to enable individuals to complete a greater number of reps to failure during short-term resistance exercise.

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Michael J. Duncan, Joanne Hankey and Alan M. Nevill

This study examined the efficacy of peak-power estimation equations in children using force platform data and determined whether allometric modeling offers a sounder alternative to estimating peak power in pediatric samples. Ninety one boys and girls aged 12–16 years performed 3 countermovement jumps (CMJ) on a force platform. Estimated peak power (PPest) was determined using the Harman et al., Sayers SJ, Sayers CMJ, and Canavan and Vescovi equations. All 4 equations were associated with actual peak power (r = 0.893−0.909, all p < .01). There were significant differences between PPest using the Harman et al., Sayers SJ, and Sayers CMJ equations (p < .05) and actual peak power (PPactual). ANCOVA also indicated sex and age effect for PPactual (p < .01). Following a random two-thirds to one-third split of participants, an additive linear model (p = .0001) predicted PPactual (adjusted R2 = .866) from body mass and CMJ height in the two-thirds split (n = 60). An allometric model using CMJ height, body mass, and age was then developed with this sample, which predicted 88.8% of the variance in PPactual (p < .0001, adjusted R2 = .888). The regression equations were cross-validated using the one-third split sample (n = 31), evidencing a significant positive relationship (r = .910, p = .001) and no significant difference (p = .151) between PPactual and PPest using this equation. The allometric and linear models determined from this study provide accurate models to estimate peak power in children.

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Wesley O’Brien, Michael J. Duncan, Orlagh Farmer and Diarmuid Lester

Recent research has shown that post-primary Irish youth are insufficiently active and fail to reach a level of proficiency across basic fundamental movement skills. The purpose of the current research was to gather cross-sectional data on adolescent youth, differentiated by gender, specifically to inform the development of a targeted movement-oriented intervention. Data were collected on adolescents (N = 219; mean age : 14.45 ± 0.96 years), within two, mixed-gender schools. Data collection included actual and perceived movement measurements comprised of fundamental movement skills, the functional movement screen, perceived movement confidence, and perceived functional confidence. Overall, levels of actual mastery within fundamental and functional movement were low, with significant gender differences observed. Adolescent males scored higher in the overall fundamental movement skill domain (male mean score = 70.87 ± 7.05; female mean score = 65.53 ± 7.13), yet lower within the functional movement screen (male mean score = 13.58 ± 2.59), in comparison to their female counterparts (female mean score = 14.70 ± 2.16). There were high levels of perceived confidence reported within fundamental and functional movement scales. Future intervention strategies should combat the low levels of actual movement skill proficiency, while identifying the reasons for higher perceived movement confidence within adolescents.

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Diego B. Souza, Michael Duncan and Marcos D. Polito

Purpose: To examine the effects of acute caffeine (CAF) intake on physical performance in 3 sets of unilateral knee extensions with blood-flow restriction. Methods: In a double-blind crossover design, 22 trained men ingested 6 mg·kg−1 of CAF or a placebo (PLA), 1 h prior to performing unilateral knee-extension exercise with blood-flow restriction until exhaustion (30% of 1 maximal repetition). Results: There was a significant difference in the number of repetitions between the CAF and PLA conditions in the first set (28.3 [5.3] vs 23.7 [3.2]; P = .005), second set (11.6 [3.1] vs 8.9 [2.9]; P = .03), and total repetitions performed across the 3 sets (44.5 [9.4] vs 35.0 [6.6]; P = .001). Blood lactate was also significantly different (P = .03) after exercise between the CAF (7.8 [1.1] mmol·L−1) and PLA (6.0 [0.9] mmol·L−1). In regard to pain perception, there was a difference between the CAF and PLA in the second (6.9 [1.5] vs 8.4 [1.4]; P = .04) and third sets (8.7 [0.4] vs 9.5 [0.6]; P = .01). No differences were found for perceived effort. Conclusion: Acute caffeine intake increases performance and blood lactate concentration and reduces perception of pain in unilateral knee-extension exercise with blood-flow restriction.

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Michael Duncan, Elizabeth Bryant, Mike Price, Samuel Oxford, Emma Eyre and Mathew Hill

This study examined postural sway in children in eyes open (EO) and eyes closed (EC) conditions, controlling for body mass index (BMI) and physical activity (PA). Sixty two children (aged 8–11years) underwent sway assessment using computerized posturography from which 95% ellipse sway area, anterior/posterior (AP) sway, medial/lateral (ML) sway displacement and sway velocity were assessed. Six trials were performed alternatively in EO and EC. BMI (kg/m2) was determined from height and mass. PA was determined using sealed pedometry. AP amplitude (p = .038), ML amplitude (p = .001), 95% ellipse (p = .0001), and sway velocity (p = .012) were higher in EC compared with EO conditions. BMI and PA were not significant as covariates. None of the sway variables were significantly related to PA. However, sway velocity during EO (p = .0001) and EC (p = .0001) was significantly related to BMI. These results indicate that sway is poorer when vision is removed, that BMI influences sway velocity, but that pedometer-assessed PA was not associated with postural sway.

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Lorayne Woodfield, Michael Duncan, Yahya Al-Nakeeb, Alan Nevill and Charles Jenkins

The present study examines the relationship of sex, ethnicity, and socio-economic status to physical activity levels of young people. Participants were 301 males and females (12.9 – 0.81 years). Physical activity was measured using the four by one-day physical activity recall questionnaire. ANOVA revealed that high socio-economic status children reported greater average daily energy expenditure levels than low socio-economic status children (p < .01). The daily energy expenditure of white-Caucasian children was significantly higher than black or Asian children. White boys were significantly more active than white girls, but no such sex differences were observed among black and Asian children. Although activity was always greater at weekends, a decline in activity by school year was observed on Saturdays and Sundays but with no such decline observed on weekdays.

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Amanda Santos, Sandra Silva-Santos, Michael Duncan, Maria João Lagoa, Susana Vale and Jorge Mota

Purposes: To examine the association between sedentary time (ST) and light physical activity (LPA), moderate- to vigorous-intensity physical activity (MVPA), and body mass index (BMI), and to track these behaviors over a 3-year follow-up in young schoolchildren. Methods: The final sample was 64 children (female: n = 36 or 56.3%), enrolled in schools in Porto, Portugal. Height and mass of children were measured by standard methods, and BMI was then calculated. ST, LPA, and MVPA were measured by accelerometer. Changes (Δ) and relative changes (Δ%) between 2009/2010 and 2012/2013 of ST, LPA, MVPA, and BMI were computed. Multiple linear regression analyses were fit to predict Δ%ST (outcome variable), by Δ%LPA, Δ%MVPA, and Δ%BMI (exposure variables). Results: ST increased and LPA decreased significantly for whole sample (both Ps < .05). No statistically significant difference was found for MVPA over time. There were no differences for ΔST, ΔLPA, ΔMVPA, and ΔBMI between boys and girls. The Δ%LPA and Δ%MVPA were negatively associated with Δ%ST, whereas Δ%BMI was positively associated. Tracking coefficients varied from moderate to strong. Conclusions: Time spent in ST increases due to displacement of time in LPA. This reinforces public health measures and suggests the need for interventions focusing on offsetting the decline ST and increasing MVPA during childhood.

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Sandra Silva-Santos, Amanda Santos, Michael Duncan, Susana Vale and Jorge Mota

Introduction: Adequate gross motor coordination is essential for children participating in age-related physical activities and has an important role in maintaining sufficient physical activity levels during the life course. Aim: To examine the association between moderate-to-vigorous physical activity (MVPA) and gross motor coordination during sedentary behavior in early childhood (ages 3–6 y). Methods: The sample comprised 209 children aged 3–6 y. Gross motor coordination was assessed according to the Movement Assessment Battery for Children (MABC-2). The battery to assess gross motor coordination comprised the aiming and catching, and balance components. MVPA was measured by accelerometry worn for 7 consecutive days (Monday to Sunday). Results: Our data indicated that 31.5% of the sample had low, 32.5% medium, and 36.0% high gross motor coordination. Multiple linear regression analysis showed that MVPA was positively associated with gross motor coordination, adjusted for gender and sedentary behavior. Conclusions: Preschoolers with high gross motor coordination spend more time in MVPA. Gross motor coordination development should therefore be a key strategy in childhood interventions aiming to promote physical activity.