Gary Skrinar | Boston University (original) (raw)

Papers by Gary Skrinar

Archives of physical medicine and rehabilitation, 1980

The primary purpose of this investigation was to determine if a safe and effective physical condi... more The primary purpose of this investigation was to determine if a safe and effective physical conditioning heart rate (HR) could prescribed by perception of exertion. Ratings of perceived exertion (RPE) were requested from 10 normal adult men during treadmill exercise trials at 4.7, 6.5, 9.7, 11.3, and 12.9km/hr (T1). Subjects were then requested to subjectively regulate their own treadmill speed during 2 separate trials (T2 and T3) at the RPE reported for each speed during T1. Speed and HR at equivalent RPE were compared during T1, T2, and T3. Regression analyses revealed that there was no difference in speed across all RPE between the 3 trials; however, HR was seen to become progressively higher during T2 and T3 than during T1 as speed and RPE decreased. HR reliability was significant (p < 0.05) during running but not significant (p > 0.05) during walking. It is concluded that prescription of exercise by RPE can produce safe, effective, and reliable conditioning HR above 150bp...

The Endocrine Society's 93rd Annual Meeting & Expo, June 4–7, 2011 - Boston, Jun 1, 2011

Medicine and Science in Sports and Exercise, May 1, 2006

PubMed, Jun 1, 1982

The pattern of changes in plasma concentrations of melatonin was followed in 7 initially untraine... more The pattern of changes in plasma concentrations of melatonin was followed in 7 initially untrained young women subjected to periodic acute exercise testing during the course of an 8 weeks' progressive aerobic exercise training program. Training comprised cycle ergometry 2 days/week and running 4 days/week for increasingly prolonged periods of intense exercise eliciting 85% of maximum heart rate. Acute exercise tests consisted of one-hour graded submaximal endurance rides on a bicycle ergometer. After a mock ride for familiarization purposes, three test rides were conducted during the early follicular phase of three consecutive menstrual cycles at the beginning, middle and end of the training program. Blood was sampled atraumatically before the rides, at their conclusion and 30 minutes into recovery. During the rides, the plasma concentrations of melatonin rose significantly above baseline control values. Exercise-enhanced melatonin levels may contribute to impaired reproductive function in women engaging in endurance sports.

Journal of Applied Physiology, Apr 1, 1988

The effect of simulated altitude erythrocythemia on hemoglobin flow rate and maximal O2 uptake (V... more The effect of simulated altitude erythrocythemia on hemoglobin flow rate and maximal O2 uptake (VO2max) was determined for nine women sea-level residents. Test conditions included normoxia and normobaric hypoxia (16% O2-84% N2). Cycle tests were performed under normoxia (T1-N) and hypoxia (T1-H) at prereinfusion control and under hypoxia 48 h after a placebo infusion (T2-H) and 48 h after autologous infusion of 334 ml of erythrocytes (T3-H). Hematocrit (38.1-44.9%) and hemoglobin concentration (12.7-14.7 g.dl-1) increased from control to postreinfusion. At peak exercise, VO2max decreased from T1-N (2.40 l.min-1) to T1-H (2.15 l.min-1) then increased at T3-H (2.37 l.min-1). Maximal arterial-mixed venous O2 difference decreased from T1-N to T1-H and increased at T3-H. Cardiac output (Q), stroke volume, heart rate, and total peripheral resistance during maximal exercise were unchanged from T1-N through T3-H. Hemoglobin flow rate (Hb flow) at maximum did not change from T1-N to T1-H but increased at T3-H. When compared with submaximal values for T1-N, VO2 was unchanged at T1-H and T3-H; Q increased at T1-H and decreased at T3-H; arterial-mixed venous O2 difference decreased at T1-H and increased at T3-H; Hb flow did not change at T1-N but increased at T3-H. For young women, simulated altitude erythrocythemia increased peak Hb flow and decreased physiological altitude (227.8 m) but did not affect maximum cardiac output (Qmax).

Journal of Applied Physiology, Jun 1, 1984

A prospective study of the hormonal effects of a moderate exercise training program (4-wk control... more A prospective study of the hormonal effects of a moderate exercise training program (4-wk control, 8-wk training) was conducted in seven young women. Sixty-minutes continuous bicycle ergometer tests of fixed relative intensity were performed at the beginning, middle, and end of the training period. The capacity of these acute bouts of exercise to affect circulating levels of stress markers, reproductive hormones, and hormones with possible antireproductive potential was measured. In addition, the urinary excretion of reproductive hormones was monitored continuously via serial overnight urine collections. Within testing sessions, plasma concentrations of all stress markers and antireproductive hormones rose significantly. Across testing sessions, only beta-endorphin + beta-lipotropin and cortisol exhibited an increment in peak responses as training progressed. Plasma reproductive hormone levels showed insignificant acute changes, and cyclic menstruation and preovulatory gonadotropin surges continued in all subjects. However, ovarian function was disturbed in four subjects as evidenced by a decreased excretion of estriol, free progesterone, or both. Transient infertility is a known clinical accompaniment of hormonal changes of comparable subtlety.

Journal of Applied Physiology, 1989

To investigate the hypothesis that endurance exercise may lead to a decrease in ventilatory chemo... more To investigate the hypothesis that endurance exercise may lead to a decrease in ventilatory chemosensitivity as possibly mediated by an increase in endogenous beta-endorphins, we measured hypercapnic ventilatory responsiveness (HCVR) and circulating beta-endorphin immunoreactivity in six runners before and after a marathon (42.2 km) race and after administration of 10 mg iv naloxone. Similar testing was performed at identical time periods on the day before the marathon as control data. On each occasion, HCVR was measured twice 15 min apart, and the mean value was used for analysis. Six active (training distance 50–104 km/wk) and experienced (no. of marathons completed, 1–25) runners participated in the study. There were no significant changes in beta-endorphin activity or HCVR on the control day. All runners experienced a rise in beta-endorphin activity from premarathon (21.3 +/- 16.0 pg/ml) to immediate postmarathon (89.6 +/- 84.9 pg/ml) values (P less than 0.05). However, HCVR sho...

Medicine & Science in Sports & Exercise, 1986

PubMed, Dec 1, 1980

Research quarterly, 1978

The purpose of this investigation was to study the effectiveness of the Golfer's Groove,1 a m... more The purpose of this investigation was to study the effectiveness of the Golfer's Groove,1 a mechanical device which restricts displacement of the golf club through a standard swing plane, as an instructional aid for beginning golf classes. Twelve beginning golfers, enrolled in a 7 1/2-week instructional series and matched according to pretest scores on a golf skill test, were randomly divided into two groups. One group received instruction using the Groove and the other group received a similar amount and type of instruction without the Groove. The Vanderhoof drive test was used to assess learning as reflected in outcome changes. Form was assessed by having golf teaching professionals rate pre and postfilms of the students using rating scales designed specifically for the study. Hotelling's matched pairs T 2 test of scores on both the Vanderhoof drive test and the film analysis disclosed no significant differences between the groups in posttest scores (p > .05). It was co...

Cardiopulmonary Physical Therapy Journal, 1994

The viability of the Wilmore Branching (WB) treadmill protocol, a graded exercise stress test tha... more The viability of the Wilmore Branching (WB) treadmill protocol, a graded exercise stress test that places individuals at different levels of exertion with respect to fitness level, was investigated as an alternative means of evaluating cardiac patients and compared to the traditional modified Bruce (BR) and Balke (BA) protocols. Twenty coronary patients who gave informed consent, ten taking no medications (non-drug) and ten taking beta or calcium channel blockers (drug), were compared to ten apparently healthy age-matched controls (C). Each patient was tested on three different occasions using each of the protocols supervised by a cardiologist. The order of protocols was randomized and assigned to patients depending upon their entry into the study. Peak oxygen uptake (VO2 peak), ventilation (VE), respiratory exchange ratio (R), ventilation threshold (Tvent) and test duration were determined for each of the protocols. Ratings of perceived exertion (RPE) were obtained to determine if patients' perceptions differed between protocols and groups. Correlational analysis indicated that the measurement of VOZ peak, VE, R, Tvent, and test duration were reproducible and not significantly different between the BR, BA, and WB protocols. Further, neither the physiological parameters measured nor the RPE responses obtained were significantly influenced by protocol or group membership as analyzed by analysis of variance (ANOVA) with repeated measures. As expected, coronary group responses to the three protocols were consistently and significantly lower (p < .05) than the age-matched controls. These results suggest that the WB protocol may be used as a plausible alternative to either the BR or BA protocols in predicting peak VOZ in a coronary population.

Abstract : The primary purpose of this investigation was to determine if a safe and effective phy... more Abstract : The primary purpose of this investigation was to determine if a safe and effective physical conditioning heart rate (HR) could be prescribed by perception of exertion. Ratings of perceived exertion (RPE) were requested from ten normal adult males during treadmill exercise trials at 4.7, 6.5, 9.7, 11.3, and 12.9 km/hr (T1). Subjects were then requested to subjectively regulate their own treadmill speed during two separate trials (T2 and T3) at the RPE reported for each speed during T1. Speed and HR at equivalent RPE were compared during T1, T2 and T3. Regression analyses revealed that there was no difference in speed across all RPE between the three trials, however, HR was seen to become progressively higher during T2 and T3 than during T1 as speed and RPE decreased. HR reliability was significant (p.05) during running but not significant (p.05) during walking. It is concluded that prescription of exercise by RPE can produce safe, effective and reliable conditioning HR above 150 beats/min (80% HR max) and running speeds above 9 km/hr (5.6 mph). Use of RPE for exercise prescription below these levels can result in inaccurate and unreliable conditioning heart rates. This method of exercise prescription has limitations and could result in dangerously high HR if used in cardiac rehabilitation programs for patients in which strict adherence to target HR is essential. (Author)

Medicine and Science in Sports and Exercise, Apr 1, 1987

Perceptual and Motor Skills, 1983

Fifteen women (20- to 23-yr.-old), engaged in an intensive 6- to 8-wk. endurance running program,... more Fifteen women (20- to 23-yr.-old), engaged in an intensive 6- to 8-wk. endurance running program, progressively increased distance from 20 miles during the first week to 50 miles during the fifth week and thereafter. Before (T1), during (T2), and after training (T3), submaximal treadmill runs of 1-hr. duration subdivided into three successive 20-min. segments were completed at approximately 60, 70, and 80% of maximal oxygen uptake, respectively. Ratings of perceived exertion (RPE) were differentiated to obtain local (L), central (C), and over-all (O) responses during these 20-min. segments. Subjects rated the effort during the final 30 sec. of each 5-min. interval. Upon completion of each exercise segment, blood samples were drawn for analysis of lactate (Hla), epinephrine (E), and norepinephrine (NE) to determine the relationship between the differentiated RPEs and these stress markers. Endurance training significantly lowered central and over-all ratings of perceived exertion betw...

Perceptual and Motor Skills, 1979

The study examined the effect of information on golf teachers' ability to determine the prese... more The study examined the effect of information on golf teachers' ability to determine the presence or absence of selected critical aspects of the golf swing. Experienced golf teachers were randomly assigned to one of two groups, knowledge of outcome ( n = 16) or no knowledge of outcome ( n = 12), in which the actual outcomes of three filmed golf swings were either verbally supplied or denied, respectively. Subjects indicated the presence or absence of six critical positions or movements of the swing for each modeled response. Results indicated that subjects who received information were not significantly more accurate than those who were not given this information. Also, there was no evidence that subjects were more confident in their analyses when outcome information was provided.