•The Copenhagen Soccer test has now been modified and applied for high-level female football players.•The physiological response and decrease in sprint performance during CSTw is comparable to ...competitive matches.•The CSTw can be used for investigation of metabolite response and fatigue mechanisms in female football.•The CSTw can also be used for intervention studies and for training and testing of injured female players.
We evaluated the physiological response, sprint performance and technical ability in various phases of the Copenhagen Soccer Test for Women (CSTw) and investigated whether the locomotor activities of the CSTw were comparable to competitive match-play (CM). Physiological measurements and physical/technical assessments were performed during CSTw for eleven Norwegian high-level women soccer players. The activity pattern during CSTw and CM was monitored using the ZXY tracking system. No differences were observed between CSTw and CM with regards to total distance covered (10093±94 and 9674±191m), high intensity running (1278±67 and 1193±115m) or sprinting (422±55 and 372±46m) (p>.05). During CSTw, average HR was 85±2%HRmax with 35±2% playing time >90%HRmax. Blood lactate increased (p<.05) from 1.4±0.3mM at rest to an average of 4.7±0.5mM during CSTw, with no changes during the test. Blood glucose was 5.4±0.3mM at rest and remained unaltered during CSTw. Sprint performance (2×20m) decreased (p<.05) by 3% during CSTw (8.19±0.06–8.47±0.10s). In conclusion, the locomotor activities during CSTw were comparable to that of high-level competitive match-play. The physiological demands of the CSTw were high, with no changes in heart rate, blood lactate or technical performance during the test, but a lowered sprint performance towards the end of the test.
Incremental tests on a treadmill are used to evaluate endurance athletes; however, no criterion exists to determine the intensity at which to start the test, potentially causing the loss of the first ...lactate threshold. This study aimed to determine the ideal speed for runners to start incremental treadmill tests. The study consisted of 94 runners who self-reported the average speed from their last competitive race (10-42.195 km) and performed an incremental test on a treadmill. The speeds used during the first three test stages were normalised in percentages of average competition speed and blood lactate concentration was analysed at the end of each stage. The relationship between speed in each stage and blood lactate concentration was analysed. In the first stage, at an intensity corresponding to 70% of the reported average race speed, only one volunteer had blood lactate concentration equal to 2 mmol·L
, and in the third stage (90% of the average race speed) the majority of the volunteers had blood lactate concentration ≥2 mmol·L
. Our results demonstrated that 70% of the average speed from the subject’s last competitive race - from 10 to 42.195 km - was the best option for obtaining blood lactate concentration <2 mmol·L
in the first stage, however, 80% of the average speed in marathons may be a possibility. Evaluators can use 70% of the average speed in competitive races as a strategy to ensure that the aerobic threshold intensity is not achieved during the first stage of incremental treadmill tests.
This study examined the effects of the intensity and duration of exercise on the nature and magnitude of training adaptations in muscle of adolescent (2-3 yr old) racehorses. Six thoroughbreds that ...had been pretrained for 2 mo performed six consecutive conditioning programs of varying lactate-guided intensities velocities eliciting blood lactate concentrations of 2.5 mmol/l (v2.5) and 4 mmol/l (v4), respectively and durations (5, 15, 25 min). Pre- and posttraining gluteus muscle biopsies were analyzed for myosin heavy chain content, fiber-type composition, fiber size, capillarization, and fiber histochemical oxidative and glycolytic capabilities. Although training adaptations were similar in nature, they varied greatly in magnitude among the different training protocols. Overall, the use of v4 as the exercise intensity for 25 min elicited the most consistent training adaptations in muscle, whereas the minimal training stimulus that evoked any significant change was identified with exercises of 15 min at v2.5. Within this range, muscular adaptations showed significant trends to be proportional to the exercise load of specific training programs. Taken together, these data suggest that muscular adaptations to training in horses occur on a continuum that is based on the exercise intensity and duration of training. The practical implications of this study are that exercises for 15 to 25 min/day at velocities between v2.5 and v4 can improve in the short term (3 wk) the muscular stamina in thoroughbreds. However, exercises of 5-15 min at v4 are necessary to enhance muscular features related to strength (hypertrophy).
To evaluate the influence of warm-up exercise intensity and subsequent recovery on intense endurance performance, selected blood variables, and the oxygen-uptake (VO2) response.
Twelve highly trained ...male cyclists (VO2max 72.4 ± 8.0 mL · min-1 · kg-1, incremental-test peak power output (iPPO) 432 ± 31 W; mean ± SD) performed 3 warm-up strategies lasting 20 min before a 4-min maximal-performance test (PT). Strategies consisted of moderate-intensity exercise (50%iPPO) followed by 6 min of recovery (MOD6) or progressive high-intensity exercise (10-100%iPPO and 2 × 20-s sprints) followed by recovery for 6 min (HI6) or 20 min (HI20).
Before PT venous pH was lower (P < .001) in HI6 (7.27 ± 0.05) than in HI20 (7.34 ± 0.04) and MOD6 (7.35 ± 0.03). At the same time, differences (P < .001) existed for venous lactate in HI6 (8.2 ± 2.0 mmol/L), HI20 (5.1 ± 1.7 mmol/L), and MOD6 (1.4 ± 0.4 mmol/L), as well as for venous bicarbonate in HI6 (19.3 ± 2.6 mmol/L), HI20 (22.6 ± 2.3 mmol/L), and MOD6 (26.0 ± 1.4 mmol/L). Mean power in PT in HI6 (402 ± 38 W) tended to be lower (P = .11) than in HI20 (409 ± 34 W) and was lower (P = .007) than in MOD6 (416 ± 32 W). Total VO2 (15-120 s in PT) was higher in HI6 (8.18 ± 0.86 L) than in HI20 (7.85 ± 0.82 L, P = .008) and MOD6 (7.90 ± 0.74 L, P = .012).
Warm-up exercise including race-pace and sprint intervals combined with short recovery can reduce subsequent performance in a 4-min maximal test in highly trained cyclists. Thus, a reduced time at high exercise intensity, a reduced intensity in the warm-up, or an extension of the recovery period after an intense warm-up is advocated.
Background: Previous studies have demonstrated that in patients with coronary artery disease (CAD) upward deflection of the heart rate (HR) performance curve can be observed and that this upward ...deflection and the degree of the deflection are correlated with a diminished stress dependent left ventricular function. Magnesium supplementation improves endothelial function, exercise tolerance, and exercise induced chest pain in patients with CAD. Purpose: We studied the effects of oral magnesium therapy on exercise dependent HR as related to exercise tolerance and resting myocardial function in patients with CAD. Methods: In a double blind controlled trial, 53 male patients with stable CAD were randomised to either oral magnesium 15 mmol twice daily (n = 28, age 61±9 years, height 171±7 cm, body weight 79±10 kg, previous myocardial infarction, n = 7) or placebo (n = 25, age 58±10 years, height 172±6 cm, body weight 79±10 kg, previous myocardial infarction, n = 6) for 6 months. Maximal oxygen uptake (VO2max), the degree and direction of the deflection of the HR performance curve described as factor k<0 (upward deflection), and the left ventricular ejection fraction (LVEF) were the outcomes measured. Results: Magnesium therapy for 6 months significantly increased intracellular magnesium levels (32.7±2.5 v 35.6±2.1 mEq/l, p<0.001) compared to placebo (33.1±3.1.9 v 33.8±2.0 mEq/l, NS), VO2max (28.3±6.2 v 30.6±7.1 ml/kg/min, p<0.001; 29.3±5.4 v 29.6±5.2 ml/kg/min, NS), factor k (−0.298±0.242 v −0.208±0.260, p<0.05; −0.269±0.336 v −0.272±0.335, NS), and LVEF (58±11 v 67±10%, p<0.001; 55±11 v 54±12%, NS). Conclusion: The present study supports the intake of oral magnesium and its favourable effects on exercise tolerance and left ventricular function during rest and exercise in stable CAD patients.
Abstract Background Centhaquin is a cardiovascular active agent that significantly reduced blood lactate levels and enhanced resuscitative effect of hypertonic saline. The present study was carried ...out to determine the resuscitative effect of centhaquin and compare that with large-volume lactated Ringer (LR) solution in hemorrhaged rats. Materials and methods Male, adult Sprague–Dawley rats were anesthetized with urethane, and a pressure catheter SPR-320 was placed in the left femoral artery; another pressure–volume catheter SPR-869 was placed into the left ventricle through carotid artery. Hemorrhage was induced by withdrawing blood from the right femoral artery, and the mean arterial pressure (MAP) was maintained at 35 mm Hg for 30 minutes after which resuscitation was performed using LR solution (LR-100) (100% shed blood volume), centhaquin (0.017, 0.05, and 0.15 mg/kg) dissolved in LR (100% shed blood volume), or LR-300 (300% shed blood volume). Arterial blood gases and cardiovascular parameters were determined before the induction of hemorrhage and at various times after hemorrhage. Results It was found that survival time after resuscitation with LR-100 was 78 ± 10 min. Centhaquin in doses of 0.017 and 0.05 mg/kg significantly improved survival time to 291 ± 57 and 387 ± 39 min, respectively. Blood lactate levels (millimoles per liter) increased from 7.22 ± 0.67 at hemorrhage to 10.20 ± 0.61 at 60 min after resuscitation with LR-100. On the other hand, blood lactate levels significantly decreased to 3.55 ± 0.07 and 4.08 ± 0.28 at 60 min after resuscitation with 0.017 and 0.05 mg/kg doses of centhaquin, respectively. Centhaquin in these doses produced a 55% and 59% increase in MAP, respectively, compared with a 29% decrease by LR-100. A decrease in systemic vascular resistance of 57% and 41% was observed with 0.017 and 0.05 mg/kg doses of centhaquin, respectively, compared with a 6% decrease by LR-100. LR-100 decreased cardiac output (CO) by 28%, whereas 0.017 and 0.05 mg/kg doses of centhaquin increased it by 260% and 180%, respectively. LR-300 commonly used for resuscitation was found to increase MAP and CO. Compared with LR-300, centhaquin (0.05 mg/kg) significantly improved survival time, increased CO, and was effective in resuscitation of hemorrhaged rats. Conclusions Centhaquin was found to be more effective than LR-300 as an effective resuscitative agent for the treatment of hemorrhagic shock in rat.
The purpose of this study was to investigate the effects of inspiratory threshold loading (ITL) and inspiratory muscle training (IMT) on blood lactate concentration (lac(-)B) and acid-base balance ...after maximal incremental cycling.
Eighteen subjects were divided into a control (n = 9) or an IMT group (n = 9). Before and after a 6-wk intervention, subjects completed two maximal incremental cycling tests followed by 20 min of recovery with (ITL) or without (passive recovery (PR)) a constant inspiratory resistance (15 cm H2O). The IMT group performed 6 wk of pressure threshold IMT at 50% maximal inspiratory mouth pressure. Throughout recovery, acid-base balance was quantified using the physicochemical approach by measuring the strong ion difference (SID = Na+ + K+ - Cl- + lac-), the total concentration of weak acids (Atot-), and the partial pressure of carbon dioxide (PCO2).
After the intervention, maximal inspiratory mouth pressure increased in the IMT group only (+34%). No differences in lactate clearance were observed between PR and ITL before the intervention in both groups and after the intervention in the control group. After IMT, relative to PR, lac-B was reduced throughout ITL (minutes 2-20) by 0.66 +/- 1.28 mmol x L(-1) (P < 0.05), and both the fast (lactate exchange) and the slow (lactate clearance) velocity constants of the lactate recovery kinetics were increased (P < 0.05). Relative to pre-IMT, ITL reduced plasma H, which was accounted for by an IMT-mediated increase in SID due almost exclusively to a 1.7-mmol x L(-1) reduction in lac-B.
After maximal exercise, ITL affected lactate recovery kinetics only after IMT. Our data support the notion that the inspiratory muscles are capable of lactate clearance that increases SID and reduces H+. These effects may facilitate subsequent bouts of high-intensity exercise.
Our understanding of what happens in working muscle and at the whole-body level at sea level and at high altitude is different from that a few years ago. If dietary CHO and nutrition are adequate, at ...sea level metabolism shifts from a mix of lipid and CHO-derived fuels toward carbohydrate (glycogen, glucose, and lactate) oxidation at moderate and greater exercise intensities. As given by the Crossover Concept, a percentage to total energy expenditure, lipid oxidation is greatest at exercise power outputs eliciting 45-50 % of VO2max with greater intensities requiring relatively more CHO and lesser lipid oxidation. At altitude, a given exercise power output is achieved at a greater relative intensity expressed as % VO2max. Hence, exercise under conditions of hypoxia requires greater glycolytic flux, and lactate production than does the same effort at sea level, normoxic conditions. Glycolytic flux is further augmented at altitude by the effect of hypoxemia on sympathetic nervous system activity. Hence, augmented lactate production during exercise is adaptive. Over the short term, accelerated lactate flux provides ATP supporting muscle contraction and balances cytosolic redox. As well, lactate provides and energy substrate and gluconeogenic precursor. Over a longer term, via redox and ROS-generating mechanisms, lactate may affect adaptations in mitochondrial biogenesis and solute (glucose and lactate) transport. While important, the energy substrate, gluconeogenic, and signaling qualities of lactate production and disposal at altitude need to be considered within the context of overall dietary energy intake and expenditure during exercise at sea level and high altitude.
The aim of this study was to describe the game characteristics and energy requirement in elite squash. Seven players (ranked 1-25 in their national federation, including the world number 1) performed ...a squash-specific incremental test to volitional exhaustion and 3 squash games simulating competition. Pulmonary gas exchanges, heart rate (HR), and blood lactate concentration (LA) were recorded by portable analyzers. Energy expenditure (EE(VO(2))) was evaluated by indirect calorimetry. Temporal structure was determined from video recordings. The mean oxygen uptake (VO(2)), HR, EE(VO(2)), and LA were 54.4 +/- 4.8 ml x min(-1) x kg(-1) (86 +/- 9% of VO(2)max reached in the incremental squash test), 177 +/- 10 beats x min(-1) (92 +/- 3% of HRmax), 4,933 +/- 620 kJ x h(-1), and 8.3 +/- 3.4 mmol x L(-1), respectively. Time spent >90% of VO(2)max and HRmax was 24 +/- 29% and 69 +/- 18% of the total match duration, respectively. LA was correlated (R = 0.87; p = 0.01) with time spent >90% of VO(2)max. The mean rally duration yielded 18.6 +/- 4.6 s, and 34.6% of the rallies were <10 s, and 32.6% were >21 s. The effective playing time was 69.7 +/- 4.7%. World-standard squash is predominantly a high-intensity aerobic activity with great emphasize on the anaerobic energy systems and a high uncertainty in the course of match play. To improve squash results, coaches should plan training according to the characteristics of the sport. By showing the contribution of the different energy pathways and variables easily controllable during training sessions (e.g., HR, rally duration, lactate), the accurate prescription of conditioning session is improved.
PDF
