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Mitchell M. Kanter

Free radicals have been implicated in the development of diverse diseases such as cancer, diabetes, and cataracts, and recent epidemic-logical data suggest an inverse relationship between antioxidant intake and cardiovascular disease risk. Data also suggest that antioxidants may delay aging, Research has indicated that free radical production and subsequent lipid peroxidation are normal sequelae to the rise in oxygen consumption with exercise. Consequently, antioxidant supplementation may detoxify the peroxides produced during exercise and diminish muscle damage and soreness. Vitamin E, beta carotene, and vitamin C have shown promise as protective antioxidants. Other ingestible products with antioxidant properties include selenium and coenzyme Q10. The role (if any) that free radicals play in the development of exercise-induced tissue damage, or the protective role that antioxidants may play, remains to be elucidated. Current methods used to assess exercise-induced lipid peroxidation are not extremely specific or sensitive; research that utilizes more sophisticated methodologies should help to answer many questions regarding dietary antioxidants.

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Margaret M. Coleman and Murray Mitchell

The purpose of this study was to develop a strategy to assess two facets of the supervisory responsibilities of Cooperating Teachers (CTs): (a) what CTs choose to observe during a lesson when preparing to offer comments to a student teacher and (b) what CTs choose to bring to the attention of student teachers after observing a lesson. The purpose also was to determine the usefulness of the strategy in discriminating among CTs that may have different preparation backgrounds for supervisory duties. Eighteen elementary level CTs participated by individually watching a videotaped lesson, preparing a written critique, and responding to interviews regarding the supervision of a student teacher. Results support the strategy used as a viable means for identifying selected supervisory abilities of CTs, facilitating the identification of discernible similarities and differences among CTs, and discriminating between two groups of CTs with different backgrounds.

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Mitchell M. Kanter and Melvin H. Williams

Three nutritional products that have very different mechanisms of action are antioxidant vitamins, carnitine, and choline. Antioxidant vitamins do not appear to have a direct effect on physical performance in well-fed people but have been touted for their ability to detoxify potentially damaging free radicals produced during exercise. Carnitine purportedly enhances lipid oxidation, increases VO2max, and decreases plasma lactate accumulation during exercise. However, studies of carnitine do not generally support its use for ergogenic purposes. Choline supplements have been advocated as a means of preventing the decline in acetylcholine production purported to occur during exercise; this decline may reduce the transmission of contraction-generating impulses across the skeletal muscle, an effect that could impair one’s ability to perform muscular work. However, there are no definitive studies in humans that justify choline supplementation. Much of the scientific data regarding the aforementioned nutrients are equivocal and contradictory. Their potential efficacy for improving physical performance remains largely theoretical.

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Murray Mitchell

Column-editor : James M. Mensch

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Hans U. Wessel, Janette F. Strasburger and Brett M. Mitchell

We have developed normal standards for the Bruce exercise (EX) protocol since a review of 875 studies in patients with congenital or acquired heart disease showed that only 5.1% achieved the predicted 50th percentile for EX time of the standards reported by Cumming, Everatt, and Hastman (Am. J Cardiol 41:69, 1978). Our data are based on 160 males and 103 females, age 4–18 years who met the following criteria: trivial or no heart disease, maximal effort, maximal EX heart rate (HR) > 180 beats/min, and normal resting and EX ECG without arrhythmia. The ECG was monitored continuously and HR computed from the ECG and the end of each minute of EX. Comparison with the predicted data of Cumming et al. for each age group by stage showed essentially identical submaximal EX heart rates but slightly lower maximal HR (–2%), which averaged 197 beats per minute in males and females. EX times were on average 15% lower than the predicted 50th percentile for most age groups in males and females. We developed regression equations, which predict exercise time from age and body size or age, body size and 2nd stage exercise heart rate. They better reflect the capabilities of untrained, asymptomatic children and adolescents seen in our laboratory in the 1990s than the Canadian data of 1978.

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M. Renée Umstattd Meyer, Stephanie L. Baller, Shawn M. Mitchell and Stewart G. Trost

Background:

Accelerometers have become one of the most common methods of measuring physical activity (PA). Thus, validity of accelerometer data reduction approaches remains an important research area. Yet, few studies directly compare data reduction approaches and other PA measures in free-living samples.

Objective:

To compare PA estimates provided by 3 accelerometer data reduction approaches, steps, and 2 self-reported estimates: Crouter’s 2-regression model, Crouter’s refined 2-regression model, the weighted cut-point method adopted in the National Health and Nutrition Examination Survey (NHANES; 2003–2004 and 2005–2006 cycles), steps, IPAQ, and 7-day PA recall.

Methods:

A worksite sample (N = 87) completed online-surveys and wore ActiGraph GT1M accelerometers and pedometers (SW-200) during waking hours for 7 consecutive days. Daily time spent in sedentary, light, moderate, and vigorous intensity activity and percentage of participants meeting PA recommendations were calculated and compared.

Results:

Crouter’s 2-regression (161.8 ± 52.3 minutes/day) and refined 2-regression (137.6 ± 40.3 minutes/day) models provided significantly higher estimates of moderate and vigorous PA and proportions of those meeting PA recommendations (91% and 92%, respectively) as compared with the NHANES weighted cut-point method (39.5 ± 20.2 minutes/day, 18%). Differences between other measures were also significant.

Conclusions:

When comparing 3 accelerometer cut-point methods, steps, and self-report measures, estimates of PA participation vary substantially.

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Nicole M. Livecchi, Charles W. Armstrong, Mitchell L. Cordova, Mark A. Merrick and James M. Rankin

Objective:

To compare average electromyogram (EMG) activity of the vastus medialis obliquus (VMO) and vastus lateralis (VL) during straight-leg raise (SLR) and knee extension (KE) with the hip in neutral and lateral rotation.

Design:

1 × 4 factorial repeated-measures.

Setting:

Laboratory.

Participants:

13 male college students.

Intervention:

SLR with hip flexed at 40°, in neutral position, and maximally laterally rotated and KE with hip in neutral and maximally laterally rotated.

Main Outcome Measure:

Average EMG activity during each of the 4 conditions, normalized against peak muscle activity during that trial.

Results:

No differences were observed between exercises in VMO activity (F3,36 = 0.646, P > .05), VL activity (F3,36 = 1.08, P > .05), or VMO:VL ratio (F3,36 = 0.598, P > .05).

Conclusions:

Electrical activity of the VMO or VL and VMO:VL ratio do not change with hip position or exercise.

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Jeffrey M. Janot, Kelly A. Auner, Talisa M. Emberts, Robert M. Kaatz, Kaelyn M. Matteson, Emily A. Muller and Mitchell Cook

Purpose:

Previous research has stated that dryland sled pulling trains first-step quickness in hockey players. Further research has demonstrated that off-ice horizontal training (sled pull, parachute, etc) relates well to on-ice acceleration and speed. However, there is limited literature pertaining to on-ice resistance training that aims to enhance speed and acceleration in hockey players. The purpose of the current study was to determine if on-ice BungeeSkate training would improve on-ice speed and acceleration in youth hockey players.

Methods:

Twenty-three Peewee and Bantam hockey players (age 11–14) were recruited, with 20 participants completing the study. Pretesting and posttesting consisted of an on-ice 44.8-m speed test, a 6.1-m acceleration test, and a 15.2-m full-speed test. The training protocol consisted of 8 sessions of 5 BungeeSkate training exercises per session, 2 times per week for a 4-wk period.

Results:

The results of this study showed that speed and top speed were significantly increased (P < .05) by 4.2% and 4.3%, respectively. Acceleration was also slightly improved but not significantly.

Conclusions:

A 4-wk BungeeSkate training intervention can improve acceleration and speed in youth hockey players. This training method could be a valid adjunct to existing strategies to improve skill development in hockey and is shown to improve speed and acceleration in relatively short training sessions. This may be most advantageous for hockey coaches and players who are looking to maximize training benefits with limited ice time.

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James M. Mensch and Murray Mitchell

Column-editor : Marisa A. Colston

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Stuart J. Cormack, Renee L. Smith, Mitchell M. Mooney, Warren B. Young and Brendan J. O’Brien

Purpose:

To determine differences in load/min (AU) between standards of netball match play.

Methods:

Load/min (AU) representing accumulated accelerations measured by triaxial accelerometers was recorded during matches of 2 higher- and 2 lower-standard teams (N = 32 players). Differences in load/min (AU) were compared within and between standards for playing position and periods of play. Differences were considered meaningful if there was >75% likelihood of exceeding a small (0.2) effect size.

Results:

Mean (± SD) full-match load/min (AU) for the higher and lower standards were 9.96 ± 2.50 and 6.88 ± 1.88, respectively (100% likely lower). The higher standard had greater (mean 97% likely) load/min (AU) values in each position. The difference between 1st and 2nd halves’ load/min (AU) was unclear at the higher standard, while lower-grade centers had a lower (−7.7% ± 10.8%, 81% likely) load/min (AU) in the 2nd half and in all quarters compared with the 1st. There was little intrastandard variation in individual vector contributions to load/min (AU); however, higher-standard players accumulated a greater proportion of the total in the vertical plane (mean 93% likely).

Conclusions:

Higher-standard players produced greater load/min (AU) than their lower-standard counterparts in all positions. Playing standard influenced the pattern of load/min (AU) accumulation across a match, and individual vector analysis suggests that different-standard players have dissimilar movement characteristics. Load/min (AU) appears to be a useful method for assessing activity profile in netball.