Three km Track Time Trial Performance Changes after HIIT in Competitive Cross-Country Skiers

Background: Limited research surrounding sex differences in fatigue and performance after high intensity interval training (HIIT) exists in the field setting. While lab-based protocols provide a controlled environment, physiological mechanisms of fatigue and performance response in competitive athletes are best measured by time-trial (TT). Few studies, however, have investigated fatigue in TT performance while controlling for the menstrual cycle (MC). Objective: The study investigated the influence of sex and MC phase on 3km track TT performance after a HIIT session in Competitive Cross Country (XC) skiers. Methods: A quasi-experimental design was employed and athletes over the age of 16 years (30F, 9M), were recruited from across Canada and completed 3 days of testing/training: a 3km track TT on Day 1 and Day 3; and a HIIT session (4-8x, 800m) on Day 2. MC phase was verified by ovulation testing and salivary hormone samples; athletes were classified as either “Low Hormone” or “High Hormone” for analysis. Results: An overall improvement in performance from pre- to post-HIIT TTs occurred (p<0.01). No significant differences in TT performance after HIIT were observed between sexes (p=0.16) or MC phase (p=0.26). Conclusion: These results indicate that competitive XC skiers will likely experience an improvement in TT performance after a bout of HIIT. Coaches and athletes should plan their workouts prior to testing accordingly to maximize TT performance. These results also suggest that no special adjustments need to be considered for differences in performance after HIIT between sexes and MC phase, although further studies with a greater sample size and repeated testing are warranted

A Game-Based Approach to Lower Blood Pressure? Comparing Acute Hemodynamic Responses to Endurance Exercise and Exergaming: A Randomized Crossover Trial

The present randomized crossover study aimed to determine whether an exergaming session in an innovative, functional fitness game could be an effective exercise approach that elicits favorable blood pressure (BP) responses, such as a typical moderate endurance exercise (ET). Therefore, acute hemodynamic responses after a training session in the ExerCube and an ET on a treadmill were assessed and compared. Twenty-eight healthy recreational active participants (13 women; aged 24.8 ± 3.9 years) completed an exergaming session (EX) and an ET in a randomized and counterbalanced order. Before and throughout the 45 min after the training, the peripheral and central BP were measured. After the ET, there was a moderate decrease in both peripheral systolic (−1.8 mmHg; p = 0.14) and diastolic (−0.8 mmHg; p = 0.003), as well as central diastolic (−1.5 mmHg; p = 0.006) pressure compared to the resting value before the exercise. After the EX, there was a significant decrease in peripheral systolic (−6.3 mmHg; p < 0.001) and diastolic (−4.8 mmHg; p < 0.001), as well as central systolic (−5.8 mmHg; p < 0.001) and diastolic (−5.3 mmHg; p < 0.001) pressure compared to baseline. The interaction effects showed significant differences in peripheral and central systolic BP as well as in peripheral diastolic BP (p = 0.05). The EX seems to be an effective training approach that triggers relevant peripheral and central BP-responses, which are more pronounced than after a typical ET. Therefore, the ExerCube can be a time-efficient training tool to improve cardiovascular health

Responses To Hyperthermia. Optimizing Heat Dissipation By Convection And Evaporation: Neural Control Of Skin Blood Flow And Sweating In Humans

Under normothermic, resting conditions, humans dissipate heat from the body at a rate approximately equal to heat production. Small discrepancies between heat production and heat elimination would, over time, lead to significant changes in heat storage and body temperature. When heat production or environmental temperature is high the challenge of maintaining heat balance is much greater. This matching of heat elimination with heat production is a function of the skin circulation facilitating heat transport to the body surface and sweating, enabling evaporative heat loss. These processes are manifestations of the autonomic control of cutaneous vasomotor and sudomotor functions and form the basis of this review. We focus on these systems in the responses to hyperthermia. In particular, the cutaneous vascular responses to heat stress and the current understanding of the neurovascular mechanisms involved. The available research regarding cutaneous active vasodilation and vasoconstriction is highlighted, with emphasis on active vasodilation as a major responder to heat stress. Involvement of the vasoconstrictor and active vasodilator controls of the skin circulation in the context of heat stress and nonthermoregulatory reflexes (blood pressure, exercise) are also considered. Autonomic involvement in the cutaneous vascular responses to direct heating and cooling of the skin are also discussed. We examine the autonomic control of sweating, including cholinergic and noncholinergic mechanisms, the local control of sweating, thermoregulatory and nonthermoregulatory reflex control and the possible relationship between sudomotor and cutaneous vasodilator function. Finally, we comment on the clinical relevance of these control schemes in conditions of autonomic dysfunction

Minimal Dose of Resistance Exercise Required to Induce Immediate Hypotension Effect in Older Adults with Hypertension:Randomized Cross-Over Controlled Trial

To determine the optimal exercise volume to generate a hypotension response after the execution of a single strength exercise in elderly subjects with hypertension (HT), a randomized crossover design was performed. A total of 19 elderly subjects with HT performed one control session and three experimental sessions of resistance training with different volumes in a randomized order: three, six, and nine sets of 20 repetitions maximum (RM) of a single elbow flexion exercise with elastic bands. The systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean heart rate (MHR) were tested at the beginning and immediately afterwards, at 30 and 60 min, and at 4, 5, and 6 h after the resistance exercise. The results show that the volumes of six and nine sets of 20 RM obtained statistically significant differences in the SBP at 30 and 60 min post-exercise (p &lt; 0.05); in the DBP at 30 min after exercise (p &lt; 0.05); and in the MHR immediately after exercise at 30 and 60 min (p &lt; 0.05), compared to a control session. A single resistance exercise with a minimum volume of six sets of 20 RM generated an acute post-exercise antihypertensive response that was maintained for 60 min in elderly people with controlled HT

Gender differences in relative and absolute expressions of orthostatic tolerance

Research concerning the central venous pressure (CVP) responses to lower body negative pressure (LBNP) is very limited, and research examining the tolerance of men and women to LBNP has yielded conflicting results. Hence, cardiovascular responses of 23 women and 20 men to LBNP tolerance were examined, with CVP measurements being taken through -60 mmHg. Variables were assessed at supine rest, while lying on their side for central venous pressure measurements, and at each (-10 mmHg) stage of LBNP through the completion of -100 mmHg or the onset of signs and symptoms of presyncope. Variables assessed included: central venous pressure, systolic and diastolic blood pressures, mean arterial pressure, pulse pressure, stroke volume, cardiac output, heart rate, total peripheral conductance, and forearm vascular conductance. Pulse pressure and mean arterial pressure were higher in the men than the women at rest, but there were no differences in the other resting cardiovascular variables. There were no significant gender by LBNP interaction for any of the variables, indicating that the men and women responded similarly to the LBNP

The changes of aortic stiffness during normal menstrual cycle

Pulse wave velocity (PWV), augmentation index (AI) and finger photoplethysmography fitness index (PPGF) are non-invasive markers of vascular function and may predict future cardiovascular disease (CVD) risk. In women, the changes from both oestrogen and progesterone levels during menstrual cycle may give significant impact on vascular function. Thus, this study was designed to investigate the variation of vascular function during follicular and luteal phase in healthy young women. Twenty-two healthy young women with regular menstrual cycle were recruited. Blood pressure (BP), body mass index (BMI), PWV, AI, PPGF, estradiol (Es) and progesterone (Prog) level were measured during follicular (F) and mid-luteal (L) phase. Data was analyzed via SPSS version 20 and P value < 0.05 was considered to be significant. The mean age of the subjects was 22.73 ± 0.60 years. There was significant variations of estradiol and progesterone levels during menstrual cycle whereby the level of estradiol (EsF = 107.6 ± 52.56 pmol/L vs. EsL = 555.16 ± 152.79 pmol/L, P<0.05) and progesterone (ProgF = 0.62 ± 0.26 nmol/L vs. ProgL = 46.74 ± 14.59 nmol/L, P<0.05) were higher in mid-luteal compared to follicular phase. PWV value was higher during follicular phase when compared to mid-luteal phase (PWVF = 6.67 ± 0.66 m/s vs. PWVL = 6.31 ± 0.52 m/s, P=0.01). The levels of BP, BMI, PPGF (PPGFF = 55.43 ± 7.50% vs. PPGFL = 56.59 ± 7.23 %, P=0.41) and AI (AIF = 12.87 ± 5.13% vs. AIL = 10.80 ± 4.52%, P=0.11) were unchanged between the two phases. In conclusion, PWV differs between follicular and mid-luteal phases of menstrual cycle in healthy young women. Thus, history of menstrual cycle must be taken into account when assessing PWV among women

The role of microcirculation in hypertension and its assessment based on skin microvasculature function testing

Zaburzenie funkcji mikrokrążenia odgrywa kluczową rolę w patofizjologii wielu schorzeń. Zmiany mikrounaczynienia obserwowano także w nadciśnieniu tętniczym. Remodeling naczyń tętniczych oraz przerzedzenie przyczyniają się w nadciśnieniu do zwiększenia oporu obwodowego. Wpływ zmian mikrokrążenia może podlegać modyfikacji przez aktywność naczynioruchową, która powoduje wahania przepływu. Analiza oscylacji przepływu może być dodatkowym elementem diagnostycznym w nadciśnieniu. Badanie skóry techniką laserowej przepływometrii dopplerowskiej umożliwia ocenę funkcji mikrokrążenia u człowieka. Metoda ta pozwala na ocenę przekrwienia po niedokrwieniu, podaniu acetylocholiny drogą jontoforezy, miejscowym stresie termicznym, a także badanie oscylacji przepływu. Tym samym umożliwia całościową ocenę funkcji mikrokrążenia i jej wykorzystanie kliniczne.Dysfunction of microcirculation play a key role in the pathophysiology of many diseases. Microvascular changes were also observed in hypertension. Arteriolar remodeling and rarefaction contribute to increase of vascular resistance in hypertensive subjects. However, microvascular effects may be modified by vasomotion, which cause flow fluctuations. Analysis of the flowmotion may serve an additional diagnostic landmark in hypertension. The study of microcirculation function can be performed in humans using laser Doppler flowmetry of the skin. The method provides assesment of postocclusive, acetylcholine iontophoresis, local thermal hyperemia and also flowmotion. The laser Doppler tests may be clinically useful for the global assessment of microvascular function

The role of microcirculation in hypertension and its assessment based on skin microvasculature function testing

Zaburzenie funkcji mikrokrążenia odgrywa kluczową rolę w patofizjologii wielu schorzeń. Zmiany mikrounaczynienia obserwowano także w nadciśnieniu tętniczym. Remodeling naczyń tętniczych oraz przerzedzenie przyczyniają się w nadciśnieniu do zwiększenia oporu obwodowego. Wpływ zmian mikrokrążenia może podlegać modyfikacji przez aktywność naczynioruchową, która powoduje wahania przepływu. Analiza oscylacji przepływu może być dodatkowym elementem diagnostycznym w nadciśnieniu. Badanie skóry techniką laserowej przepływometrii dopplerowskiej umożliwia ocenę funkcji mikrokrążenia u człowieka. Metoda ta pozwala na ocenę przekrwienia po niedokrwieniu, podaniu acetylocholiny drogą jontoforezy, miejscowym stresie termicznym, a także badanie oscylacji przepływu. Tym samym umożliwia całościową ocenę funkcji mikrokrążenia i jej wykorzystanie kliniczne. Nadciśnienie Tętnicze 2010, tom 14, nr 5, strony 395-410.Dysfunction of microcirculation play a key role in the pathophysiology of many diseases. Microvascular changes were also observed in hypertension. Arteriolar remodeling and rarefaction contribute to increase of vascular resistance in hypertensive subjects. However, microvascular effects may be modified by vasomotion, which cause flow fluctuations. Analysis of the flowmotion may serve an additional diagnostic landmark in hypertension. The study of microcirculation function can be performed in humans using laser Doppler flowmetry of the skin. The method provides assesment of postocclusive, acetylcholine iontophoresis, local thermal hyperemia and also flowmotion. The laser Doppler tests may be clinically useful for the global assessment of microvascular function. Arterial Hypertension 2010, vol. 14, no 5, pages 395-410