Acute responses of platelet count and ADP-induced platelet aggregation to different high intensity interval exercise modes

The effects of type of recovery in resistance exercise on responses of platelet indices and hemodynamic variables

To examine the effects of two different volume-matched resistance exercise (RE) recovery protocols (passive and active) on platelet indices and hemodynamic variables. Twelve Healthy participants (mean ± SD; 25 ± 3 yrs) completed a traditional resistance exercise (TRE) protocol that included three sets of six repetitions at 80% one repetition maximum (1RM) with two minutes passive recovery between sets, exercises and an interval resistance exercise (IRE) protocol that included three sets of six repetitions at 60%1RM followed by active recovery including six repetitions of the same exercise at 20%1RM. Blood samples for multiple platelet indices were taken before the protocols, immediately-post (IP), and after 1-hour recovery. Hemodynamic variables were measured before, IP, and every five minutes during recovery. Mean platelet volume and platelet large cell ratio P_LCR decreased from baseline to recovery. Heart rate (HR) and rate pressure product (RPP) were augmented at IP following IRE compared to TRE. HR was significantly elevated for 20 minutes after both RE protocols, and RPP recovered by five minutes. Systolic blood pressure was increased at IP compared to baseline and all recovery time points for both RE protocols. Our research demonstrated that both RE protocols, produced transient increases in platelet indices (MPV, and P_LCR) and hemodynamic variables (SBP, HR, and RPP), all of which returned to baseline within an hour. Notably, the IRE protocol elicited a greater increase in HR and RPP compared to the TRE protocol.

Fasting for 20 h does not affect exercise-induced increases in circulating BDNF in humans

Intermittent fasting and exercise provide neuroprotection from age-related cognitive decline. A link between these two seemingly distinct stressors is their capability to steer the brain away from exclusively glucose metabolism. This cerebral substrate switch has been implicated in upregulating brain-derived neurotrophic factor (BDNF), a protein involved in neuroplasticity, learning and memory, and may underlie some of these neuroprotective effects. We examined the isolated and interactive effects of (1) 20-h fasting, (2) 90-min light exercise, and (3) high-intensity exercise on peripheral venous BDNF in 12 human volunteers. A follow-up study isolated the influence of cerebrovascular shear stress on circulating BDNF. Fasting for 20 h decreased glucose and increased ketones (P ≤ 0.0157) but had no effect on BDNF (P ≥ 0.4637). Light cycling at 25% of peak oxygen uptake ( V ̇ O 2 peak ${\dot V_{{{\rm{O}}_{\rm{2}}}{\rm{peak}}}}$ ) increased serum BDNF by 6 ± 8% (independent of being fed or fasted) and was mediated by a 7 ± 6% increase in platelets (P < 0.0001). Plasma BDNF was increased from 336 pg l^-1 [46,626] to 390 pg l^-1 [127,653] by 90-min of light cycling (P = 0.0128). Six 40-s intervals at 100% of V ̇ O 2 peak ${\dot V_{{{\rm{O}}_{\rm{2}}}{\rm{peak}}}}$ increased plasma and serum BDNF, as well as the BDNF-per-platelet ratio 4- to 5-fold more than light exercise did (P ≤ 0.0044). Plasma BDNF was correlated with circulating lactate during the high-intensity intervals (r = 0.47, P = 0.0057), but not during light exercise (P = 0.7407). Changes in cerebral shear stress - whether occurring naturally during exercise or induced experimentally with inspired CO₂ - did not correspond with changes in BDNF (P ≥ 0.2730). BDNF responses to low-intensity exercise are mediated by increased circulating platelets, and increasing either exercise duration or particularly intensity is required to liberate free BDNF. KEY POINTS: Intermittent fasting and exercise both have potent neuroprotective effects and an acute upregulation of brain-derived neurotrophic factor (BDNF) appears to be a common mechanistic link. Switching the brain's fuel source from glucose to either ketone bodies or lactate, i.e. a cerebral substrate switch, has been shown to promote BDNF production in the rodent brain. Fasting for 20 h caused a 9-fold increase in ketone body delivery to the brain but had no effect on any metric of BDNF in peripheral circulation at rest. Prolonged (90 min) light cycling exercise increased plasma- and serum-derived BDNF irrespective of being fed or fasted and seemed to be independent of changes in cerebral shear stress. Six minutes of high-intensity cycling intervals increased every metric of circulating BDNF by 4 to 5 times more than prolonged low-intensity cycling; the increase in plasma-derived BDNF was correlated with a 6-fold increase in circulating lactate irrespective of feeding or fasting. Compared to 1 day of fasting with or without prolonged light exercise, high-intensity exercise is a much more efficient means to increase BDNF in circulation.

RECOVERY METHODS FOR ATHLETES DURING HIGH-INTENSITY TRAINING

ABSTRACT Introduction: The continuous improvement of the level of modern sports competition compels continuous reform and constant updates on sports training theory; sports training research is migrating from continuous low-intensity to high-intensity interval, and many studies have shown that high-intensity interval training has a good effect on athletes. Objective: Investigate the effect of different recovery modalities during high-intensity interval training on the athletic performance of young male runners. Methods: Using body morphological index measurement, high-intensity intermittent exhaustion test, and statistical analysis, forty young male long-distance runners from sports schools were randomly divided into active recovery group (AR, n=20) and passive recovery group (PR, n=20), maximal oxygen uptake (VO2max) and maximal aerobic speed (MAV) were measured by incremental load exercise test, and interval exercise capacity and time to exhaustion (ET) were recorded. Results: Compared with pre-training, MAV and ET in both groups increased significantly after training (P<0.05); there was no significant difference in MAV on RA group after training (P>0.05). Conclusion: High-intensity interval training with active recovery can significantly improve athletic ability and performance in young male runners in the long term. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Water-soluble tomato concentrate modulates shear-induced platelet aggregation and blood flow in vitro and in vivo

Water-soluble tomato concentrate (WSTC), extracted from mature tomatoes, is the first health product in Europe that has been approved “to help maintain normal platelet activity to maintain healthy blood flow.” We hypothesized that WSTC might exert an influence on blood flow shear stress-induced platelet aggregation (SIPA) and in turn maintains healthy blood flow. We used a microfluidic system to measure the effects of WSTC on SIPA in vitro. We also used the strenuous exercise rat model and the κ-carrageenan-induced rat tail thrombosis model to demonstrate the effects of WSTC on blood flow. WSTC significantly inhibited platelet aggregation at pathological high shear rate of 4,000 s–1 and 8,000 s–1in vitro (P &lt; 0.05 or P &lt; 0.01). WSTC reduced the platelet adhesion rate and increased the rolling speed of platelets by inhibiting binding to Von Willebrand Factor (vWF) (P &lt; 0.05 or P &lt; 0.01). The oral administration of WSTC for 4 weeks in strenuous exercise rats alleviated hyper-reactivity of the platelets and led to a significant reduction in the plasma levels of catecholamine and IL-6. WSTC treatment also led to a reduction in black tail length, reduced blood flow pulse index (PI) and vascular resistance index (RI), and ameliorated local microcirculation perfusion in a rat model of thrombosis. WSTC exerted obvious inhibitory effects on the platelet aggregation induced by shear flow and alleviated the blood flow and microcirculation abnormities induced by an inflammatory reaction.

Investigation of the effect of training on serotonin, melatonin and hematologic parameters in adolescent basketball players

OBJECTIVES

Exercise can improve both health and mood. Some beneficial effects of exercise are attributed to endocrine status. This study aims to evaluate the effect of eight weeks of basketball training on melatonin, serotonin, and hematologic parameters in basketball players.

METHODS

The experimental group was selected form 34 healthy young boys, aged between 13 and 16 years old. The participants were randomly assigned to the control group (n=17) and the exercise group (n=17). The exercise program consisted of 2 h/day aerobic activity of basketball training in 5 days a week for 8 weeks. Venous blood was taken on the day before experiment (pre-exercise) and on the day following the last exercise (post-exercise) and hormone levels were detected by ELISA.

RESULTS

Serotonin and melatonin levels significantly increased in the post-exercise group compared to the other groups (p<0.05). Exercise caused increase in WBC, RBC, HCT and Hb levels (p<0.05) while did not alter PLT, MCH, and PCT levels (p>0.05). This study indicates that an eight weeks-long regular aerobic exercise increased melatonin and serotonin levels, and also altered some hematological parameters.

CONCLUSIONS

In conclusion, it is believed that improvement in levels of serotonin, melatonin, and hematological parameters after eight weeks of regular basketball training in basketball players could be attributed to beneficial effects of exercise. Investigation in other branches of sports and in different gender and age groups would make contribution into exercise physiology and training science.