Individual fluctuations in blood lactate concentration during an ice hockey game; differences between player positions

Source at:https://digitalcommons.wku.edu/ijes/vol15/iss6/13The main purpose of the current study was to provide an in-depth description of individual player’s intra-game physiological responses during an ice hockey game. A secondary aim was to compare these responses between forwards and defensemen. Six elite junior ice hockey players, three forwards and three defensemen, median (interquartile range) 17 (17–17) years, 182 (180– 185) cm, and 78 (74– 80) kg were recruited to participate in the study. Capillary blood samples were taken following each shift and analyzed for blood lactate concentration (BLC). Heart rate (HR) was registered continuously throughout the game. The game was filmed and shift lengths were determined retrospectively using a time-motion analysis. All players had BLC ranging between 1.8 and 10.7 mmol/L (mean = 5.5 mmol/L), with forwards reaching a significantly higher value than defensive players (F1, 32 = 75.2, p < 0.0001), a significant effect of time was also observed (F2, 25 = 6.4, p = 0.0058). During the game, the players accumulated 11:18 ± 5:04 (minutes:seconds) above 90% of their maximal heart rate (HRmax), but the majority of the time was below 80% of HRmax. The fluctuations in BLC and heart rate demonstrate that the intensity is highly variable during games and challenges both aerobic and anaerobic metabolic pathways. The higher BLC of forwards might indicate that they perform more high-intensity work during games than defensive players

Individual Fluctuations In Blood Lactate Concentration During An Ice Hockey Game; Differences Between Player Positions

International Journal of Exercise Science 15(6): 985-993, 2022. The main purpose of the current study was to provide an in-depth description of individual player’s intra-game physiological responses during an ice hockey game. A secondary aim was to compare these responses between forwards and defensemen. Six elite junior ice hockey players, three forwards and three defensemen, median (interquartile range) 17 (17–17) years, 182 (180–185) cm, and 78 (74– 80) kg were recruited to participate in the study. Capillary blood samples were taken following each shift and analyzed for blood lactate concentration (BLC). Heart rate (HR) was registered continuously throughout the game. The game was filmed and shift lengths were determined retrospectively using a time-motion analysis. All players had BLC ranging between 1.8 and 10.7 mmol/L (mean = 5.5 mmol/L), with forwards reaching a significantly higher value than defensive players (F1, 32 = 75.2, p \u3c 0.0001), a significant effect of time was also observed (F2, 25 = 6.4, p = 0.0058). During the game, the players accumulated 11:18 ± 5:04 (minutes:seconds) above 90% of their maximal heart rate (HRmax), but the majority of the time was below 80% of HRmax. The fluctuations in BLC and heart rate demonstrate that the intensity is highly variable during games and challenges both aerobic and anaerobic metabolic pathways. The higher BLC of forwards might indicate that they perform more high-intensity work during games than defensive players

Skeletal muscle mitochondrial DNA content and aerobic metabolism in patients with antiretroviral therapy-associated lipoatrophy

Objectives To assess whether mitochondrial dysfunction in skeletal muscle characterizes antiretroviral therapy (ART)-associated lipoatrophy (LA). Methods A cross-sectional study comparing HIV-infected, antiretroviral-treated patients with LA (n = 5; LA+) and without LA (n = 5; non-LA) was conducted. Positron emission tomography was used to measure blood flow, oxygen extraction and oxygen consumption in quadriceps femoris muscle during rest and aerobic exercise. Mitochondrial DNA (mtDNA) was quantified by PCR. Body composition was measured by dual-energy X-ray absorptiometry and magnetic resonance imaging. All data are given as means ± SEM. Results Compared with the non-LA group, the LA+ group had significantly less limb fat and more intra-abdominal fat, but similar leg muscle mass. The LA+ group versus the non-LA group had reduced mtDNA content per nucleus in adipose tissue (173 ± 38 versus 328 ± 62; P = 0.067), but not in skeletal muscle (2606 ± 375 versus 2842 ± 309; P = 0.64). Perfusion in resting muscle (34 ± 7 versus 28 ± 6 mL/kg/min in the LA+ group versus the non-LA group; P = 0.5), and the mean absolute (277 ± 30 versus 274 ± 43 mL/kg/min, respectively; P = 0.95) and relative (10.6 ± 2.5- versus 11.9 ± 1.5-fold change, respectively; P = 0.67) increases in perfusion during exercise were similar between the groups. Oxygen consumption at rest (2.2 ± 0.7 versus 2.1 ± 0.3 mL/kg/min in the LA+ group versus the non-LA group; P = 0.9), and the mean absolute (14.6 ± 1.7 versus 24.3 ± 8.8 mL/kg/min, respectively; P = 0.3) and relative (10.3 ± 2.8- versus 11.7 ± 2.4-fold change, respectively; P = 0.73) exercise-induced increases in oxygen consumption were similar between the groups. The oxygen extraction fraction was comparable between the groups, both at rest and during exercise. Plasma lactate concentrations remained unchanged in both groups during exercise. Conclusions HIV-infected patients with ART-associated LA have similar mtDNA content in skeletal muscle and comparable skeletal muscle aerobic exercise metabolism to antiretroviral-treated non-lipoatrophic patient

Plasma ceramides predict cardiovascular death in patients with stable coronary artery disease and acute coronary syndromes beyond LDL-cholesterol

Peer reviewe

Metabolic Regulation in Progression to Autoimmune Diabetes

Recent evidence from serum metabolomics indicates that specific metabolic disturbances precede β-cell autoimmunity in humans and can be used to identify those children who subsequently progress to type 1 diabetes. The mechanisms behind these disturbances are unknown. Here we show the specificity of the pre-autoimmune metabolic changes, as indicated by their conservation in a murine model of type 1 diabetes. We performed a study in non-obese prediabetic (NOD) mice which recapitulated the design of the human study and derived the metabolic states from longitudinal lipidomics data. We show that female NOD mice who later progress to autoimmune diabetes exhibit the same lipidomic pattern as prediabetic children. These metabolic changes are accompanied by enhanced glucose-stimulated insulin secretion, normoglycemia, upregulation of insulinotropic amino acids in islets, elevated plasma leptin and adiponectin, and diminished gut microbial diversity of the Clostridium leptum group. Together, the findings indicate that autoimmune diabetes is preceded by a state of increased metabolic demands on the islets resulting in elevated insulin secretion and suggest alternative metabolic related pathways as therapeutic targets to prevent diabetes

Training and illness characteristics of crosscountry skiers transitioning from junior to senior level

Objective This study aimed to describe the endurance training and incidence of illnesses reported by a group of well-trained cross-country (XC) skiers throughout their transition from junior to senior level. Methods Changes in self-reported training and performance, from 31 well-trained XC skiers, were analyzed from the start of the season they turned 16 y until the end of the season they turned 22 y, using linear mixed-effects models. Differences in the incidence of self-reported illness episodes were analyzed using incidence rate ratios, and the relationships between selfreported illness and training volumes were analyzed using linear mixed-effects models in a sub-group of 23 of the skiers. Results In total, 145 seasons of training data (including 85,846 h of endurance training) and 109 person- years of illness data (including 380 self-reported illness episodes) were analyzed. The athletes progressively increased their annual endurance training volume from age 16 to 22 y in a linear fashion, from ~ 470 to 730 h. Low- and high-intensity training volumes increased by 51.4 ± 2.4 h·y-1 (p &lt; .001) and 4.9 ± 0.6 h·y-1 (p &lt; .001), respectively. Sport-specific and non-specific training increased by 50.0 ± 2.2 h·y-1 (p &lt; .001) and 4.6 ± 2.0 h·y-1 (p &lt; .001), respectively. The athletes reported a median (range) of 3 (0-8) illness episodes and 17 (0- 80) days of illness per year, and there was an inverse relationship between self-reported illness days and annual training volume (-0.046 ± 0.013 d?h-1; p &lt; .001). Conclusions This group of well-trained XC skiers increased their endurance training volume in a linear fashion by ~ 55 h annually. This was primarily achieved through an increase in low-intensity and sport-specific training. Furthermore, higher training volumes were associated with a lower number of self-reported illness days

Individual Fluctuations in Blood Lactate Concentration During an Ice Hockey Game; Differences Between Player Positions.

The main purpose of the current study was to provide an in-depth description of individual player's intra-game physiological responses during an ice hockey game. A secondary aim was to compare these responses between forwards and defensemen. Six elite junior ice hockey players, three forwards and three defensemen, median (interquartile range) 17 (17-17) years, 182 (180-185) cm, and 78 (74-80) kg were recruited to participate in the study. Capillary blood samples were taken following each shift and analyzed for blood lactate concentration (BLC). Heart rate (HR) was registered continuously throughout the game. The game was filmed and shift lengths were determined retrospectively using a time-motion analysis. All players had BLC ranging between 1.8 and 10.7 mmol/L (mean = 5.5 mmol/L), with forwards reaching a significantly higher value than defensive players (F 1, 32 = 75.2, p &lt; 0.0001), a significant effect of time was also observed (F 2, 25 = 6.4, p = 0.0058). During the game, the players accumulated 11:18 ± 5:04 (minutes:seconds) above 90% of their maximal heart rate (HRmax), but the majority of the time was below 80% of HRmax. The fluctuations in BLC and heart rate demonstrate that the intensity is highly variable during games and challenges both aerobic and anaerobic metabolic pathways. The higher BLC of forwards might indicate that they perform more high-intensity work during games than defensive players

Individual Fluctuations in Blood Lactate Concentration During an Ice Hockey Game; Differences Between Player Positions.

The main purpose of the current study was to provide an in-depth description of individual player's intra-game physiological responses during an ice hockey game. A secondary aim was to compare these responses between forwards and defensemen. Six elite junior ice hockey players, three forwards and three defensemen, median (interquartile range) 17 (17-17) years, 182 (180-185) cm, and 78 (74-80) kg were recruited to participate in the study. Capillary blood samples were taken following each shift and analyzed for blood lactate concentration (BLC). Heart rate (HR) was registered continuously throughout the game. The game was filmed and shift lengths were determined retrospectively using a time-motion analysis. All players had BLC ranging between 1.8 and 10.7 mmol/L (mean = 5.5 mmol/L), with forwards reaching a significantly higher value than defensive players (F 1, 32 = 75.2, p &lt; 0.0001), a significant effect of time was also observed (F 2, 25 = 6.4, p = 0.0058). During the game, the players accumulated 11:18 ± 5:04 (minutes:seconds) above 90% of their maximal heart rate (HRmax), but the majority of the time was below 80% of HRmax. The fluctuations in BLC and heart rate demonstrate that the intensity is highly variable during games and challenges both aerobic and anaerobic metabolic pathways. The higher BLC of forwards might indicate that they perform more high-intensity work during games than defensive players

Rifle and aiming point accelerations do not differ between the most and least accurate shots in biathlon shooting within an athlete

Study aim: As studies from shooting disciplines other than biathlon have observed associations between weapon accelerations and shooting performance, this study investigated whether accelerations of the rifle stock and aiming point (the point on the target where the rifle is aimed at) are associated with shooting performance, and differences in rifle and aiming point accelerations between the most and least accurate shots. Further, associations between rifle and aiming point accelerations were studied. Materials and methods: Shooting performance (HitDist, hit point distance from the center of the target) along with rifle and aiming point accelerations were measured from nine biathletes who performed 6×5 biathlon prone and standing shots. Results: In the prone posture, rifle or aiming point accelerations were neither associated with shooting performance nor with each other. In the standing posture, vertical rifle accelerations right before triggering were negatively associated with HitDist (r = –0.70, p < 0.05), whereas aiming point accelerations were not associated with HitDist. Horizontal rifle accelerations were positively associated with aiming point accelerations in standing (r = 0.74, p = 0.024), whereas vertical or resultant rifle accelerations did not demonstrate associations with aiming point accelerations. In both postures, rifle accelerations were of the same magnitude in the most and least accurate shots. Conclusion: Rifle and aiming point accelerations provide limited description of the technical level in biathlon shooting. Moreover, rifle accelerations alone do not appear to provide sufficient information to deduce the aiming point movements. Angular movement would likely be required for aiming point movement estimation.peerReviewe

Performance‐determining factors in biathlon prone shooting without physical stress

This study investigated the most important factors determining biathlon prone shooting performance. 10 female and 16 male biathletes (age 19.9 ± 2.9 years) from the national teams of Finland and Vuokatti-Ruka Sports Academy performed 65 biathlon prone shooting shots without physical stress under laboratory conditions. Shooting performance and multiple aiming point trajectory variables were measured together with an analysis of triggering force. Based on the aiming point trajectory data principal component analysis, we identified four technical components in biathlon prone shooting: stability of hold, aiming accuracy, cleanness of triggering and timing of triggering. Multiple regression analysis further determined that cleanness of triggering, aiming accuracy and timing of triggering accounted for 80% of mean shooting performance (p < 0.001). Better stability of hold, aiming accuracy and cleanness of triggering were directly associated with better shooting performance (0.62 ≤ |r| ≥ 0.79, all p < 0.001). Better stability of hold measures were also associated with better cleanness of triggering, and higher pre-shot trigger force levels were associated with better stability of hold and cleanness of triggering. These results indicate that with both direct and indirect effects on performance, stability of hold seems to be a general prerequisite for successful biathlon shooting. The results also highlight the importance of aiming accuracy, cleanness and timing of triggering, along with a high pre-shot trigger force level. The variables identified in this study could be used to assess biathletes’ performance in the most relevant shooting technical aspects to guide the emphasis of their shooting training.peerReviewe