Biomedical subjects

Timothy J Quinn

Publications and source records attributed to Timothy J Quinn.

6 recordsLinked to original sources

PubMed2006

Two short, daily activity bouts vs. one long bout: are health and fitness improvements similar over twelve and twenty-four weeks?

This study sought to determine whether a 12-week intermittent (INT; 2 x 15 min.d(-1)) exercise program yielded similar improvements in cardiovascular health and fitness, compared with a traditional 12-week, 30-minute continuous (CON; 1 x 30 min.d(-1)) exercise program. A second purpose was to determine the effects of switching exercise programs and continuing training for an additional 12 weeks. Twenty women and 17 men, (age 48.8 +/- 9.0 years) were divided randomly into 2 groups: INT (n = 20) and CON (n = 17). Aerobic exercise was performed 4 d.wk(-1) for 12 weeks. Subjects then crossed over to the opposite training program for an additional 12 weeks of training. Subjects exercised incrementally for weeks 1-4 and training was conducted at 70-80% heart rate reserve for weeks 5-24. Both groups showed comparable exercise adherence, completing 96.6 +/- 12.2% (CON) and 96.3% +/- 17.7% (INT) of the prescribed exercise time. The INT walked at a lower percentage of Vo(2)max, maximum heart rate, systolic blood pressure, and diastolic blood pressure (p < 0.05). Maximal oxygen consumption increased by 4.5% in CON and by 8.7% in INT. Following the second 12 weeks, Vo(2)max increased by 3.6 and 7.7% in CON and INT, respectively. Treadmill test time increased by 41 seconds in CON (p < 0.05) and 71 seconds in INT (p < 0.05) after 12 weeks of training. High-density lipoproteins significantly increased in the INT group following the first 12 weeks of training. This study suggests that an INT exercise program, which is incremental in nature, provides comparable, and in some cases greater, health and fitness benefits than those expected following traditional CON exercise training.

Adult↗

PubMed2006

The impact of different pacing strategies on five-kilometer running time trial performance.

The purpose of this study was to determine the optimal 1.63-km (1-mile) pacing strategy for 5-km running performance in moderately trained women distance runners. Eleven women distance runners (20.7 +/- 0.8 years, 163.8 +/- 2.0 cm, 57.0 +/- 2.2 kg, 51.7 +/- 1.0 ml.kg(-1).min(-1), 18.9 +/- 0.8% fat, 78.1 +/- 1.4% VO(2)max at lactate threshold) performed 2 preliminary 5-km time trials on a treadmill to establish baseline 5-km times. The average 1.63-km split pace of the fastest preliminary trial was manipulated for the first 1.63 km of the experimental trials and run either equal to (EVEN), 3% faster than (3%), or 6% faster than (6%) the current baseline average 1.63-km pace for each subject. Ventilation (V(E)), oxygen consumption VO(2)max )), respiratory exchange ratio, and heart rate were measured continuously. Overall 5-km times were not different (p > 0.05) for the EVEN, 3% and 6% trials finishing in 21:11 (minutes/seconds) +/- 29 seconds, 20:52 +/- 36 seconds and 20:39 +/- 29 seconds, respectively. The fastest time for 8 subjects resulted from the 6% trial and the other 3 subjects' fastest times resulted from the 3% trial. The overall exercise intensity (%VO(2)max , %VO(2)max above lactate threshold, V(E), and respiratory exchange ratio) of the first 1.63-km split was not different between the 3 and 6% trials, despite the 6% trial being 13 seconds faster than the 3% trial. Based on these findings, initial 1.63-km starting paces of a 5-km race can be 3 to 6% greater than current average race pace without negatively impacting performance. In order to optimize 5-km performance, runners should start the initial 1.63 km of a 5-km race at paces 3-6% greater than their current average race pace.

Adult↗

PubMed2004

Hypohydration effects on thermoregulation during moderate exercise in the cold.

Hyperosmotic hypovolemia impairs vasoconstriction during sedentary cold exposure. The purpose of this study was to determine whether hypohydration alters thermoregulation and cardiovascular responses to exercise in cold air. On four occasions, eight males [35.1 (2.7) years, 175.5 (3.1) cm, 73.3 (2.6) kg, 57.2 (2.6) ml kg(-1) min(-1) maximal oxygen uptake (VO(2max)), 19.6 (2.4)% fat] walked, in t-shirt, shorts, and shoes, at 50% VO(2max), for 60 min in either a 4 degrees C (Cold) or a 25 degrees C (Temperate) environment in both hypohydrated state (HYPO, -4% body mass) and euhydrated state (EU). During exercise-cold stress, rectal temperature ( T(re)), mean weighted skin temperature, heart rate (HR), cardiac output (CO), and stroke volume (SV) were measured every 20 min. Mean weighted skin temperature values were not different between HYPO and EU but were lower ( P<0.05) in Cold versus Temperate trials. T(re) was not different ( P>0.05) between HYPO-Cold and EU-Cold. CO and SV were not different within hydration states and were not different between Cold and Temperate trials ( P<0.05). HR was not different between HYPO-Cold and EU-Cold. These data demonstrate that moderate intensity exercise in the cold while hypohydrated does not alter metabolic heat production, skin temperatures and heat loss, nor does it increase thermoregulatory and cardiovascular strain.

Adult↗

PubMed2002

Placenta accreta postpartum.

BACKGROUND: Placenta accreta is the abnormal attachment of the placenta to the uterus. It occurs when the decidua basalis is either absent or incomplete. It is uncommon and most often presents with a retained placenta and hemorrhage. CASE: A 29-year-old gravida 1 had an uncomplicated antenatal course and delivery. The third stage of labor was complicated by a retained placenta necessitating manual removal. Her postpartum course was complicated by a persistent endometritis. The diagnosis of placenta accreta was made with the help of sonohysterography. CONCLUSION: Sonohysterography is a useful tool in discriminating a solid intracavitary mass from a placenta accreta postpartum.

Adult↗

PubMed2002

Infant acceptance of breast milk after maternal exercise.

OBJECTIVE: Previous research reported that breast milk lactic acid (LA) levels increase after lactating women complete a bout of exhaustive exercise, resulting in poor infant acceptance of the postexercise breast milk. This highly publicized finding may not apply to more practical, everyday exercise conditions of lactating women. The purpose of the present study was to reexamine the composition and infant acceptance of postexercise breast milk while controlling maternal diet, exercise intensity, and the method, timing, and assessment of infant feeding. RESEARCH DESIGN AND METHODS: Twenty-four women, 2 to 4 months' postpartum, completed 3 test sessions: a maximal oxygen uptake test, a 30-minute bout of moderate exercise, and a resting control session. One hour before and 1 hour after each session, participants fully expressed their milk, placed it in a bottle familiar to the infant, fed their infant, and rated their infant's acceptance of the milk. Each feeding was videotaped and viewed individually by 3 lactation consultants who rated infant acceptance; consultants were blinded to the test sessions. Milk was analyzed for LA and infant milk consumption was measured. RESULTS: There were no differences in presession versus postsession values for maternal skin temperature, breast milk temperature, and infant milk acceptance as judged by either the mothers or lactation consultants. These results prevailed despite a small but significant increase in breast milk LA premaximal versus postmaximal exercise (0.09 vs 0.21 mM, respectively); there was no difference in milk LA premoderate versus postmoderate exercise, or prerest versus postrest. CONCLUSION: These data support the hypothesis that moderate or even high-intensity exercise during lactation does not impede infant acceptance of breast milk consumed 1 hour postexercise.

Adult↗

PubMed2002

Hypohydration adversely affects lactate threshold in endurance athletes.

The purpose of this investigation was to observe the effect of hypohydration (-4% body mass) on lactate threshold (LAT) in 14 collegiate athletes (8 men and 6 women; age, 20.9 +/- 0.5 years; height, 171.1 +/- 2.4 cm; weight, 64.8 +/- 2.3 kg; V(O)2 max, 62.8 +/- 1.9 ml x kg(-1) x min(-1); percentage of fat, 11.4 +/- 1.5%). Subjects performed 2 randomized, discontinuous treadmill bouts at a dry bulb temperature (T(db)) of 22 degrees C to volitional exhaustion in 2 states of hydration, euhydrated and hypohydrated. The hypohydrated condition was achieved in a thermally neutral environment (T(db), 22 degrees C; humidity, 45%), with exercise conducted at a moderate intensity as defined by rating of perceived exertion (RPE, approximately 12) 12-16 hours before testing. On average, subjects decreased 3.9% of their body mass before the hypohydration test. Blood lactate, hematocrit, V(O)2, minute ventilation (VE), R value, heart rate (HR), and RPE were measured during each 4-minute stage of testing. In the hypohydrated condition, LAT occurred significantly earlier during exercise and at a lower absolute V(O)2, VE, respiratory exchange ratio, RPE, and blood lactate concentration. Also, the blood lactate concentration was significantly lower in the hypohydrated condition (6.7 +/- 0.8 mmol) compared with the euhydrated condition (10.2 +/- 0.9 mmol) at peak exercise. There were no differences in HR or percentage of maximum HR at LAT nor did plots of V(CO2):V(O)2 reveal differences in bicarbonate buffering during exercise between the 2 conditions. From these results, we speculate that hypohydration did not significantly alter cardiovascular function or buffering capacity but did cause LAT to occur at a lower absolute exercise intensity.

Adult↗