Pre-hypertension (pre-HT) (Blood Pressure (BP) ≥120/80mmHg to ≤ 140/90mmHg) increases the risk of developing hypertension (HT). BP reductions following acute exercise are known as post exercise hypotension (PEH). BP and perhaps PEH shows a daily circadian rhythm. Purpose: To compare the magnitude of PEH after morning and evening aerobic exercise in adults with pre-HT. Hypothesis: The magnitude of PEH will be larger after evening versus morning exercise. Participants: Pre-HT men and women 50-65 years old. Study Design: Participants engaged in cycling exercise (60% VO2max) on two occasions: 1.5 and 11 hours following waking. Cardiovascular function was assessed for 30 minutes pre and one hour post exercise. Results: 1) Systolic PEH responses affected by TOD differed by gender. 2) Baseline Heart Rate Variability and its response to exercise differed gender but not TOD. The inconsistent significant gender and TOD differences of PEH and its mechanisms suggest that this group.

Aerobic exercise is recommended as a lifestyle intervention to reduce blood pressure (BP) in individuals with elevated BP (SBP/DBP >120/80 mmHg). However, the BP response is highly variable after both acute (SBP/DBP: –27 to 9/-8 to 7mmHg) and chronic aerobic exercise (-20 to 9/ -11 to 11.3mmHg). We attempt to identify those who are resistant or responsive to training based on their responses to acute (one-bout) exercise. 17 prehypertensive (120 to 139/80 to 89mmHg) males and females (45-60yrs) underwent acute exercise assessments before and after an 8-week walking/jogging program. The magnitude of change in BP after acute exercise significantly correlated (r=.89, p < .01) with the magnitude of change in resting BP after the training. The antihypertensive mechanisms (total peripheral resistance, baroreflex sensitivity) for acute exercise were not correlated to those for chronic exercise. Central cardiovascular controls may link BP reductions after both acute and chronic exercise.

Aerobic exercise such as cycling is known to elicit a post-exercise hypotensive (PEH) response. However, it is not known if swim exercise produces a similar effect in normotensive individuals. We tested the hypothesis that an acute bout of swimming would elicit a PEH response that is less compared to an equivalent bout of cycling. 10 trained and 11 untrained normotensive (SBP/DBP < 120/80 mmHg) individuals (23±1 years) underwent 30 min intensity-matched cycling and swimming sessions to assess changes in BP and cardiovascular responses. While PEH was similar between modalities within groups, the magnitude and temporality of change in BP following swimming was significantly different (p < 0.01) between groups, with untrained participants showing a significant PEH response. Attenuation of PEH in trained individuals was reflective of a significant increase in sympathetic outflow and slower vagal reactivation, suggesting training in an aquatic environment leads to alterations in post-exercise BP regulatory mechanisms.

Current knowledge indicates that nonthermal muscle metaboreflex activity plays a critical role in the modulation of skin vasodilation and sweating. However, the mechanisms of control have primarily been studied during isometric handgrip exercise in which muscle metaboreceptor activation is induced by a brief post-exercise ischemia of the upper limb. While the reflex increase in mean arterial pressure associated with this period of ischemia is consistent with the activation of muscle metaboreceptors, the change in baroreflex activity may in itself modulate the response. Thus, we sought to understand how these nonthermal stimuli interact in modulating the control of skin perfusion and sweating under conditions of elevated hyperthermia. Furthermore, we examined the mechanisms responsible for the maintenance of arterial blood pressure under varying levels of heat stress during isometric handgrip exercise. Our study findings indicate that the parallel activation of muscle metaboreceptors and baroreceptors during post-exercise ischemia causes divergent influences on the control of skin blood flow and sweating; and these nonthermal stimuli are dependent on the level of hyperthermia. Moreover, we report that heat stress reduces the increase in arterial blood pressure during isometric handgrip exercise and this attenuation is attributed to a blunted increase in peripheral resistance, since cardiac output increased to similar levels for all heat stress conditions. These results provide important insight and understanding into the role of muscle metabo- and baroreflex activity on the control of skin blood flow and sweating; along with further knowledge into the cardiovascular mechanisms responsible for the regulation of arterial blood pressure during hyperthermia.

To optimize muscle blood flow to the skeletal muscle during exercise, the vascular bed of the muscle is partially protected from sympathetic nervous activity (SNA) vasoconstriction via a phenomenon termed functional sympatholysis. Functional sympatholysis has been documented during exercise periods in human skeletal muscle. However, it remains unknown whether functional sympatholysis is specific to the exercising period, or if it may persist for a period of time following skeletal muscle exercise. Through this study, we aimed to confirm the presence and duration of post-exercise functional sympatholysis in the human skeletal muscle. The cold pressor test (CPT) was administered to 9 male (mean age = 21.1 ± 0.8 years) participants at various time points during four different experimental trials (Rest, Exercise, Recovery 1 and Recovery 2). Exercise consisted of 7 minutes of moderate isometric handgrip exercise (15% below critical power). Heart rate (HR) and mean arterial pressure (MAP) were recorded continuously throughout each trial. Brachial artery mean blood velocity measurements as well as brachial artery diameter measurements were recorded on each participant’s exercising arm throughout each trial. Deep venous blood samples were drawn pre- and post-CPT administration from a catheter inserted into an antecubital vein of each participant’s non-experimental arm. The cardiovascular response to the CPT was repeatable across experimental days as it consistently resulted in MAP elevations regardless of the experimental time point of administration. The CPT also resulted in a significant elevation in plasma norepinephrine concentration from 0.49 ± 0.04 ng/mL at “pre-CPT” measurement to 0.66 ± 0.05 ng/mL at the end of the CPT in the Rest trial (P < 0.05). The percentage reduction in forearm vascular conductance (FVC) due to CPT administration during Exercise (4.5 ± 6.6%) and Recovery 1 (4 minutes post-exercise; -11.6 ± 8.8%) was significantly blunted in comparison to that measured during Rest (-34.8 ± 7.4%) (P < 0.05). The percentage change in FVC during the Recovery 2 trial (10 minutes post-exercise; -20.1 ± 7.1%) was not significantly different from that measured at Rest. These findings support the concept of a lingering presence of functional sympatholysis 4 minutes, but not 10 minutes, post-moderate exercise. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2011-12-21 17:17:09.037

Current knowledge indicates that nonthermal muscle metaboreflex activity plays a critical role in the modulation of skin vasodilation and sweating. However, the mechanisms of control have primarily been studied during isometric handgrip exercise in which muscle metaboreceptor activation is induced by a brief post-exercise ischemia of the upper limb. While the reflex increase in mean arterial pressure associated with this period of ischemia is consistent with the activation of muscle metaboreceptors, the change in baroreflex activity may in itself modulate the response. Thus, we sought to understand how these nonthermal stimuli interact in modulating the control of skin perfusion and sweating under conditions of elevated hyperthermia. Furthermore, we examined the mechanisms responsible for the maintenance of arterial blood pressure under varying levels of heat stress during isometric handgrip exercise. Our study findings indicate that the parallel activation of muscle metaboreceptors and baroreceptors during post-exercise ischemia causes divergent influences on the control of skin blood flow and sweating; and these nonthermal stimuli are dependent on the level of hyperthermia. Moreover, we report that heat stress reduces the increase in arterial blood pressure during isometric handgrip exercise and this attenuation is attributed to a blunted increase in peripheral resistance, since cardiac output increased to similar levels for all heat stress conditions. These results provide important insight and understanding into the role of muscle metabo- and baroreflex activity on the control of skin blood flow and sweating; along with further knowledge into the cardiovascular mechanisms responsible for the regulation of arterial blood pressure during hyperthermia.

abstract: PURPOSE: Lean hypertension (HTN) is characterized by a mechanistically different HTN when compared to obese HTN. The purpose of this study is to assess whether body phenotype influences blood pressure (BP) responses following both acute and chronic exercise. METHODS: Obese (body mass index (BMI) > 30 kg/m2) and lean (BMI < 25 kg/m2) men with pre-hypertension (PHTN) (systolic BP (SBP) 120 - 139 or diastolic BP (DBP) 80 - 89 mm Hg) were asked to participate in a two-phase trial. Phase 1 assessed differences in post-exercise hypotension between groups in response to an acute exercise bout. Phase 2 consisted of a two-week aerobic exercise intervention at 65-70% of heart rate (HR) max on a cycle ergometer. Primary outcome measures were: brachial BP, central (aortic) BP, cardiac output (CO), and systemic vascular resistance (SVR) measured acutely after one exercise session and following two weeks of training. RESULTS: There were no differences between groups for baseline resting brachial BP, central BP, age, or VO2 peak (all P > 0.05). At rest, obese PHTN had greater CO compared to lean PHTN (6.3 ± 1 vs 4.7 ± 1 L/min-1, P = 0.005) and decreased SVR compared to lean PHTN (1218 ± 263 vs 1606 ± 444 Dyn.s/cm5, P = 0.003). Average 60-minute post-exercise brachial and central SBP reduced by 3 mm Hg in Lean PHTN in response to acute exercise (P < 0.005), while significantly increasing 4 mm Hg for brachial and 3 mm Hg for central SBP (P < 0.05). SVR had a significantly greater reduction following acute exercise in lean PHTN (-223 Dyn·s/cm5) compared to obese PHTN (-75 Dyn·s/cm5, P < 0.001). In lean subjects chronic training reduced brachial BP by 4 mm Hg and central BP by 3 mm Hg but training had no effect on the BP’s in obese subjects. Resting BP reduction in response to training was accompanied by reductions in SVR within lean (-169 Dyn·s/cm5, P < 0.001), while obese experienced increased SVR following training (47 Dyn·s/cm5, P < 0.001). CONCLUSION: Hemodynamic response to both acute and chronic exercise training differ between obese and lean individuals. / Dissertation/Thesis / Doctoral Dissertation Exercise Science 2016

Current knowledge indicates that nonthermal muscle metaboreflex activity plays a critical role in the modulation of skin vasodilation and sweating. However, the mechanisms of control have primarily been studied during isometric handgrip exercise in which muscle metaboreceptor activation is induced by a brief post-exercise ischemia of the upper limb. While the reflex increase in mean arterial pressure associated with this period of ischemia is consistent with the activation of muscle metaboreceptors, the change in baroreflex activity may in itself modulate the response. Thus, we sought to understand how these nonthermal stimuli interact in modulating the control of skin perfusion and sweating under conditions of elevated hyperthermia. Furthermore, we examined the mechanisms responsible for the maintenance of arterial blood pressure under varying levels of heat stress during isometric handgrip exercise. Our study findings indicate that the parallel activation of muscle metaboreceptors and baroreceptors during post-exercise ischemia causes divergent influences on the control of skin blood flow and sweating; and these nonthermal stimuli are dependent on the level of hyperthermia. Moreover, we report that heat stress reduces the increase in arterial blood pressure during isometric handgrip exercise and this attenuation is attributed to a blunted increase in peripheral resistance, since cardiac output increased to similar levels for all heat stress conditions. These results provide important insight and understanding into the role of muscle metabo- and baroreflex activity on the control of skin blood flow and sweating; along with further knowledge into the cardiovascular mechanisms responsible for the regulation of arterial blood pressure during hyperthermia.

Thesis (M Sport Sc (Sport Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: It is well-known that acute and chronic aerobic and resistance exercise results in decreased blood pressure (BP) in hypertensive individuals. There is little evidence that water exercise has a similar effect on BP response. There is also no certainty regarding the magnitude and duration of post exercise hypotension (PEH) after either land or water-based exercise. Most studies were also performed under controlled laboratory conditions and very few characterised the PEH response under real life conditions. The current study endeavoured to examine the magnitude and duration of PEH after an acute session of water- and land-based exercise during free living conditions in persons with mild to moderate hypertension. Twenty-one men and women (aged 52 ± 10 years) volunteered for the study. All participants were pre-hypertensive or hypertensive. Participants completed a no exercise control session, a water exercise session and a combined aerobic and resistance land exercise session in random order. After all three sessions, participants underwent 24 hour monitoring using an Ergoscan ambulatory BP monitoring device. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) were monitored to determine changes from resting values after each session and to compare the PEH responses between land and water exercise. Overall, the land exercise treatment caused a 3.6 mmHg lower average SBP over 24 hours than the control treatment (P = 0.04). The average difference over 24 hours between the water and control treatments was 2.2 mmHg and between land and water exercise it was 1.5 mmHg (P > 0.05). During daytime, both land and water exercise resulted in significantly lower SBP (12.7 and 11.3 mmHg) compared to the control session (2.3 mmHg). The PEH response lasted for 24 hours after land exercise and nine hours after water exercise. There was no difference in the daytime DBP for the three treatments (P > 0.05). Although all three groups showed significant reductions during night time, both exercise treatments showed greater nocturnal falls in SBP, DBP and MAP than the control treatment. / AFRIKAANSE OPSOMMING: Dit is alombekend dat akute en chroniese aërobiese- en weerstandsoefening tot ‘n afname in bloeddruk (BD) lei in persone met hipertensie. Daar is egter min getuienis dat wateroefening dieselfde effek op die bloeddruk respons het. Daar is ook nie sekerheid oor die grootte en duur van post-oefening hipotensie na water- of landoefening nie. Die meeste studies is onder gekontrolleerde laboratorium omstandighede gedoen en min resultate is beskikbaar onder alledaagse lewensomstandighede. Die huidige studie het gepoog om die grootte en duur van die post-oefening hipotensie respons in persone met ligte tot matige hipertensie onder alledaagse omstandighede na ‘n akute sessie van water- en landgebaseerde oefening te ondersoek. Een-en-twintig mans en vrouens (ouderdom 52 ± 10 jaar) het ingewillig om aan die studie deel te neem. Alle deelnemers was hipertensief of pre-hipertensief. Alle deelnemers het ‘n kontrolesessie, ‘n wateroefeningsessie en ‘n gekombineerde aërobiese en weerstands landoefensessie, in lukrake volgorde, voltooi. Na elke sessie het die deelnemers 24 uur bloeddrukmonitering met ‘n Ergoscan wandelende bloeddruk monitor ondergaan. Sistoliese bloeddruk (SBD), diastoliese bloeddruk (DBD), gemiddelde arteriële bloeddruk en harttempo (HT) is gemonitor om die veranderinge vanaf rustende waardes na elke sessie te bepaal en om die hipotensiewe respons na land- en wateroefening te vergelyk. Landoefening het ‘n 3.6 mmHg laer gemiddelde SBD oor 24 uur tot gevolg gehad in vergelyking met die kontrolesessie (P = 0.04). Die gemiddelde verskil oor 24 uur tussen die water- en kontrolesessies was 2.2 mmHg en 1.5 mmHg tussen die land en water oefensessies (P > 0.05). Gedurende die dag het beide die land- and wateroefening gelei tot beduidende laer SBD (12.7 en 11.3 mmHg) in vergelyking met die kontrolesessie (2.3 mmHg). Die post-oefening hipotensie het 24 uur geduur na die landoefening en nege uur na die wateroefening. Daar was geen verskil in DBD gedurende die dag tussen die drie groepe nie (P > 0.05).

Thesis (M Sport Sc (Sport Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Post-exercise recovery has become an important area in research due to the high demands placed on competitive athletes. Different recovery strategies are used by athletes during competition and training. For the competitive athlete it is important to maintain performances during competition and also to enhance performances during training. However, if the athlete fails to recovery from daily exhaustive training and competition, inadequate recovery may lead to poor performances, burn-out, sickness and even injuries. There is very little evidence available on the possible performance recovery effects of the use of water immersion during multi days of intensive endurance training. Theoretically, water immersion should aid the overall recovery process without any additional energy cost involved as with active recovery. The objective of this investigation was to determine whether water immersion (cold water vs. neutral) has any effects on the post-exercise recovery rate of competitive cyclists during 3 days of intensive endurance training and whether recovery with water immersion is more effective than active recovery. Seventeen competitive cyclists (mean ± SD age: 27.6 ± 5.94 years, weight: 78.8 ± 6.67 kg, height: 180.5 ± 4.42 cm VO2max: 49.8 ± 4.13 L.min-1.kg-1, and PPO: 352.6 ± 35.94 Watts) completed 3 days of intensive endurance cycling sessions. Cyclists were randomly assigned to either a 20 minute ice bath (IB) (n = 6, 11 ± 0.9oC), neutral bath (NB) (n = 6, 30 ± 0.6oC), or active recovery (AR) (n = 5; 81 ± 1.74% of HRLT ) which were performed directly after the training sessions on Day 1 and 2. Dependent variables such as anaerobic performance, creatine kinase concentrations (CK), c-reactive protein concentrations (CRP), blood lactate concentrations, muscle soreness (VAS) and perceived fatigue (POMS), and limb circumferences were measured prior to the training sessions at Day 1, 2 and 3. In addition, changes in exercise performances over the last 2 days were also assessed. There were significant increases over the three days in plasma [CK] (P < 0.05) and [CRP] (P < 0.001) demonstrating that muscle damage and inflammation occurred during and after the training sessions. However, there were no treatment or interaction effects observed for any of the dependent variables for any of the recovery interventions (P > 0.05). Blood [La] was significantly reduced on Day 2 for the IB group in comparison to the NB group (P < 0.05). A strong tendency was observed for [CK] when the IB and NB groups were combined (WG), indicating that AR had a strong tendency to enhance the recovery of [CK] in comparison to the WG (P = 0.05). Also, there were no significant time or interaction effects observed in % changes in performances for the last two 100km TTs between Day 2 and 3 for any of the recovery interventions (P > 0.05). These findings suggest that neither cold water, nor neutral water therapy, have more beneficial effects on post-exercise recovery rates compared to active recovery. Importantly, however, is that the cyclists’ were able to maintain their performances over the three consecutive days, indicating that water therapy per se is not detrimental to endurance performance. / AFRIKAANSE OPSOMMING: Na-oefening herstel het ‘n belangrike area van navorsing geword, aangesien die eise wat aan elite atlete gestel word buitengewoon hoog is. Vir die kompeterende fietsryer is dit baie belangrik om prestasie tydens kompetitisie asook tydens inoefening te handhaaf. Inteendeel, as die atleet nie daarin slaag om effektief te herstel na daaglikse oefening en kompetisie nie, mag dit lei tot swak prestasie, uitbranding, siekte en beserings. Tot hede is daar geen baie min bewyse beskikbaar oor die potensiële voordele van waterterapie vir die herstel van atlete, veral tydens meervoudige dae van intensiewe uithouvermoë inoefening. Teoreties behoort waterterapie die algehele herstelproses bevorder sonder dat enige addisionele energiekostes betrokke is, soos in die geval van aktiewe herstel. Die doel van die ondersoek was om vas te stel of waterterapie (koud teenoor neutraal) enige effekte het op die na-oefening hersteltempo van kompeterende fietsryers tydens 3 dae van intensiewe uithouvermo oefening en om te bepaal of waterterapie meer effektief is as aktiewe herstel. Sewentien kompeterende fietsryers (gemiddeld ± SD; ouderdom: 27.6 ± 5.94 jaar, gewig: 78.8 ± 6.67 kg, lengte: 180.5 ± 4.42 cm, VO2maks: 49.8 ± 4.13 L.min-1.kg-1, en Piek krag uitset: 352.6 ± 35.94 Watts) het 3 dae van intensiewe uithouvermoë inoefeing voltooi. Die fietryers was lukraak ingedeel in ‘n 20 minute Ysbadgroep (IB) (n = 6, 11 ± 0.9oC), neutrale bad groep (NB) (n = 6, 30 ± 0.6oC) en ‘n aktiewe herstelgroep (AR) (n = 5; 81 ± 1.74% van HRLT), Herstelsessies het op Dag 1 en 2 direk na die inoefeningsessies plaasgevind. Afhanklike veranderlikes soos funksionele kapasiteit, kreatienkinase konsentrasies (CK), c-reaktiewe proteïen konsentrasies (CRP), bloedlaktaat konsentrasie ([La]), spierseerheid en persepsie van vermoeienis (STEMS), en beenomtrekke was gemeet voor die inoefeningsessies op Dag 1, 2 en 3. Veranderinge in oefeningprestasie oor die laaste 2 dae was ook geassesseer. Daar was ‘n statistiese betekenisvolle toename in plasma [CK] (P < 0.05) en [CRP] (P < 0.001) oor die drie dae, wat daarop wys dat spierskade en inflammasie wel plaasgevind het. Daar was geen behandeling of interaksie effekte waarneembaar vir enige van die intervensies nie (P > 0.05). Bloed [La] was beduidend verlaag op Dag 2 vir die IB groep in vergelyking met die NB groep (P = 0.05). Die verlaging in plasma [CK] na AR het gegrens aan statisties betekenisvolle resultate (P = 0.05) in vergelyking met die waterterapie (IB en NB gekombineer). Daar was geen statisites beduidende tyd of interaksie effekte waargeneem in die % veranderinge in oefeningprestasie vir die laaste twee 100km tydtoetse tussen Dag 2 en 3 vir enige van die herstelstrategieë nie (P < 0.05) Die resultate wys dat waterterapie nie enige voordelige effekte op die na-inoefening herstel tempo het in vergelyking met aktiewe herstel nie. Dit is egter belangrik om daarop te let dat die fietsryers in staat was om hul oefeningprestasies te handhaaf oor die drie opeenvolgende dae, wat aandui dat waterterapie nie nadelig inwerk op uithouvermoë prestasie nie.