Gymnastik- och idrottshögskolan, GIH

Altitude training enhances haematological adaptations and endurance at sea level, typically requiring exposure to similar to 2500 m altitude for 3-4 weeks. Emerging evidence suggests that low-dose carbon monoxide (CO) inhalation might mimic hypoxia and might be used by elite athletes. In this study, we examine whether periodic low-dose CO exposure can replicate the live-high, train-low model in well-trained individuals, focusing primarily on haematological and performance effects of CO exposure, with haematological markers commonly used to interpret haemoglobin mass changes discussed as exploratory. Eight well-trained individuals (four males and four females) participated in a randomized crossover study. They completed two training blocks of 4 weeks at sea level: one with CO inhalation (INCO) to simulate live-high, train-low and one with ambient air as a control (AIR), separated by a 6 month washout. Haematological variables, in vivo muscle oxidative capacity and performance metrics were assessed before and after each intervention. After INCO, haemoglobin mass (p = 0.018; +53.6 +/- 10.8 g. vs. +0.8 +/- 11.8 g), red blood cell volume (p = 0.032; +156.6 +/- 66.7 mL vs. -65.1 +/- 50.7 mL) and blood volume (p = 0.036; +240.4 +/- 120.5 mL vs. -208.3 +/- 167.5 mL) increased significantly compared with AIR. INCO significantly reduced immature reticulocytes (p = 0.04), but muscle oxidative capacity and performance metrics remained unchanged. These findings suggest that daily low-dose CO exposure at sea level over 4 weeks enhanced haematological adaptations more than standard training but did not affect muscle oxidative capacity or performance.

Purpose: Altitude training is a common strategy used with the intent to increase hemoglobin mass (Hbmass) in athletes. However, if the Hbmass is increased during altitude camps it seems to decline rapidly upon returning to sea level. This study aimed to examine the efficacy of three weekly heat training sessions over a 3.5-week period following a 3-week altitude camp, on the maintenance of Hbmass in elite cyclists.

Methods: Eighteen male cyclists (maximal oxygen consumption: 76 ± 5 mL·min-1·kg-1) underwent a 3-week altitude training camp at ∼2100 m above sea level. After the camp, participants were divided into one group performing three weekly heat sessions that was subtracted from their usual training (HEAT) while the other continuing usual training (CON). Training characteristics were recorded during the intervention, while hematological measurements were recorded before the camp as well as two days and 3.5-weeks after the altitude camp.

Results: The 3-week altitude camp led to an overall increase in total Hbmass of 4.1%. Afterwards, HEAT maintained Hbmass (0.2%, p = 0.738), while CON group experienced a significant reduction (-3.3%, p < 0.001) (ΔHEAT vs. ΔCON, p < 0.001). Moreover, HEAT increased plasma volume (PV) by 11.6% (p = 0.007) and blood volume (BV) by 5.8% (p = 0.007), whereas CON only showed an increase in PV (5.5%, p = 0.041). Exercise intensity and training load were not different between groups during the maintenance period.

Conclusions: This study suggests that incorporating three weekly heat training sessions into the usual training routine preserves a moderately increased Hbmass in elite cyclists following an altitude camp. © Lippincott Williams & Wilkins.

This study aimed to evaluate in vivo oxidative capacity and relative resistance to O2 diffusion using near-infrared spectroscopy (NIRS) in the m. triceps brachii of recreational to world class swimmers and evaluate their relationships with swimming performance. Twenty-eight swimmers were enrolled and assigned into three subgroups according to their level: 'recreational/trained' (Tier 1/2; n = 8), 'national' (Tier 3; n = 12) and 'international/world class' (Tier 4/5; n = 8). Performance was evaluated by 100 m freestyle trials. Training volume was measured by self-reported distance (km/week). The mV̇O2 recovery k of m. triceps brachii was non-invasively estimated by NIRS through repeated intermittent occlusions under two conditions: well-oxygenated (k_HIGH) and low O₂ availability (k_LOW). The difference between k_HIGH and k_LOW (Δk) was calculated as an index of relative resistance to O₂ diffusion. FINA points and 100 m performance differed among all groups. Training volume was greater in Tier 4/5 (34.0 ± 5.5 km week^-1) and Tier 3 (35.5 ± 11.6 km week^-1) than in Tier 1/2 (6.4 ± 1.8 km week^-1). k_HIGH was greater in Tier 4/5 and Tier 3 (3.18 ± 0.41 and 2.79 ± 0.40 min^-1) versus Tier 1/2 (2.10 ± 0.36 min^-1; all P < 0.002). k_HIGH correlated with FINA points, 100 m performance and training volume. ∆k was not different among tiers and was not associated with training volume or performance. M. triceps brachii oxidative capacity (k_HIGH) was positively associated with performance and training volume in swimmers. ∆k, which reflects relative resistance to O₂ diffusion, was not different among athletes. These data suggest that m. triceps brachii oxidative capacity is associated with swimming performance and that muscle O₂ diffusing capacity exerts a similar relative resistance to O₂ diffusive flow across swimmers.

Physiological characteristics such as VO_2max, running economy (RE), maximal aerobic speed (MAS), maximal sprinting speed (MSS), anaerobic speed reserve (ASR), and player profiling (based on MSS and MAS) have been proven to be important for training prescriptions in football. However, previous studies on player profiling have neglected the absolute values of MSS and MAS. The objectives of this study were to compare the aforementioned physiological variables among player roles, create benchmarks, and provide normative data to help coaches categorize players, ultimately proposing a new player profiling method. We analyzed 195 male professional football players (50 forwards, 59 midfielders, 44 full-backs, and 42 center-backs). Multivariate analysis of variance with Tukey's post hoc tests revealed positional differences. Center-backs exhibited lower VO_2max than midfielders and full-backs. Both center-backs and forwards showed poorer RE and MAS compared to midfielders and full-backs. Full-backs achieved higher MSS than midfielders and center-backs, and forwards outperformed center-backs. Finally, midfielders demonstrated lower ASR than all other positions. Benchmarks based on T-scores for all variables were provided. Finally, in the new profiling method proposed-also based on T-scores-players were classified as "speed", "endurance", or "hybrid" if their MAS and/or MSS T-score exceeded 60, "in development" if both were below 45, and "average" if both scores were between 45 and 60 without any value above 60. The normative data provided can assist coaches in identifying specific areas for improvement in players' physical conditioning-particularly valuable for youth athletes or those returning from injury. Additionally, the new profiling method offers insights into individual player characteristics, enabling more tailored and effective training interventions.

Aim: This study aimed to investigate the determinants of running performance in a cross-country running race and examine whether running economy and biomechanics are affected. Moreover, we analyzed whether the magnitude of change in running economy (RE) is related to changes in biomechanics, performance, and fitness measures. Method: Thirteen runners (12 male and 1 female), with an average 10 km personal best time of 36:46 +/- 3:17 (min:s), participated in the 30 km cross-country race, Lidingoloppet. Assessments of submaximal and maximal running physiology, biomechanics, and anthropometry were conducted before and immediately after the race. A multiple linear regression model was applied to explain performance variance. Pearson's correlation analyses examined the relationships between performance and pre-test variables, and between changes in running economy and both pre-test fitness measures and changes in biomechanics. Paired Student's t-tests were used to compare pre- and post-race values. Results: Performance was best explained using a model including oxygen uptake at lactate threshold (LT), fat utilization, and allometrically scaled running economy (R-2 = 0.918, adjusted R-2 = 0.887, F = 29.7, p < 0.01). Race performance also correlated with maximal oxygen uptake (VO(2)max, r = -0.776, p = 0.003), fat mass (r = 0.646, p = 0.032), and velocity at VO(2)max (vVO(2)max, r = -0.853, p < 0.01). The oxygen cost of running increased (201.8 +/- 14 vs. 208.4 +/- 9.3 mL kg(-1)<middle dot>km(-1); p = 0.041), whereas respiratory exchange ratio (0.91 +/- 0.04 vs. 0.85 +/- 0.05; p < 0.01) and body mass (69.2 +/- 7.5 vs. 67.6 +/- 7.7 kg; p < 0.01) decreased post-race. Energetic cost of running (0.997 +/- 0.076 vs. 1.015 +/- 0.052 kcal kg(-1)<middle dot>km(-1); p = 0.192) and all biomechanical measurements, including cadence, contact time, overstride, vertical displacement, and vertical force, were unaffected by the race. The magnitude of change in running economy was related only to pre-test running economy (r = -0.749; p = 0.003) but not to performance (r = -0.440; p = 0.132), other pre-test fitness measures, or any changes in biomechanics. Conclusion: The best performance prediction model included oxygen uptake at estimated lactate threshold, fat utilization during submaximal running, and allometrically scaled running economy. Oxygen cost of running increased post-race, likely due to increased fat oxidation, despite decreased body mass. No changes in biomechanics were observed, and changes in running economy could not be explained by changes in biomechanics. Aerobic fitness, anthropometry, and performance were not associated with changes in running economy. Given the small and relatively homogeneous sample, findings should be considered exploratory, although they suggest that practitioners may benefit from targeting fat oxidation, oxygen uptake at the estimated lactate threshold, and running economy in training.

Classifying athletes based on estimates of biological maturation (i.e., bio-banding) as a supplement to traditional age grouping has been shown to be a potential tool for enriching player development in team sports; however, bio-banding has not yet been evaluated in ice hockey. The primary aim was to investigate player experiences and coaches' selection preferences in bio-banding versus age-banding in a group of 12-13-year-old (early growth spurt) male elite players (n = 69). We also examined the relationship between somatic maturity, expressed as a % predicted adult height (%PAH), and fitness performance. Bio-banding was assessed using a questionnaire and 29 coaches selected their top players in each game based on age or bio-bands. %PAH correlated with grip strength (r = .57, p>0.001) and jumping power (r = .63, p<0.001), but not with vertical jump height, sprint time or endurance. Players who played against more mature players in bio-bands than in age groups experienced higher demands, while players who played against less mature players were able to utilize their skills to a greater extent. Coaches generally favored later-than-average maturing players who performed better on performance tests and chronologically older players in bio-banding. We conclude that bio-banding in youth ice hockey has some promising effects and warrants further evaluation.

BACKGROUND: Patients diagnosed with pancreatic, biliary tract, and liver cancer often suffer from a progressive loss of muscle mass. Given the considerable functional impairments in these patients, high musculoskeletal weight loads may not be well tolerated by all individuals. The use of blood-flow restricted resistance training (BFR-T) which only requires low training loads may allow for a faster recovery of muscle due to avoidance of high levels of mechanical muscle stress associated with high-load resistance exercise. This study aims to investigate whether BFR-T can prevent or slow down the loss of skeletal muscle mass and enhance the functional capacity and mental health of patients with pancreatic, biliary tract, and liver cancer.

METHODS: The PREV-Ex exercise trial is a multicenter two-armed randomized controlled trial. Patients will be randomized to an exercise program consisting of home-based low-load BFR-T during a combined pre- and postoperative period for a total of 6-10 weeks (prehabilitation and rehabilitation), or to a control group. Protein supplementation will be given to both groups to ensure adequate protein intake. The primary outcomes, skeletal muscle thickness and muscle cross-sectional area, will be assessed by ultrasound. Secondary outcomes include the following: (i) muscle catabolism-related and inflammatory bio-markers (molecular characteristics will be assessed from a vastus lateralis biopsy and blood samples will be obtained from a sub-sample of patients); (ii) patient-reported outcome measures (self-reported fatigue, health-related quality of life, and nutritional status will be assessed through validated questionnaires); (iii) physical fitness/performance/activity (validated tests will be used to evaluate physical function, cardiorespiratory fitness and maximal isometric muscle strength. Physical activity and sedentary behavior (assessed using an activity monitor); (iv) clinical outcomes: hospitalization rates and blood status will be recorded from the patients' medical records; (v) explorative outcomes of patients' experience of the exercise program which will be evaluated using focus group/individual interviews.

DISCUSSION: It is worthwhile to investigate new strategies that have the potential to counteract the deterioration of skeletal muscle mass, muscle function, strength, and physical function, all of which have debilitating consequences for patients with pancreatic, biliary tract, and liver cancer. The expected findings could improve prognosis, help patients stay independent for longer, and possibly reduce treatment-related costs.

TRIAL REGISTRATION: ClinicalTrials.gov NCT05044065. Registered on September 14, 2021.

Altitude training is a cornerstone for endurance athletes for improving blood variables and performance with optimal effects observed at ⁓2300-2500 meters above sea level (m.a.s.l.). However, elite cyclists face challenges such as limited access to such altitudes, inadequate training facilities, and high expenses. To address these issues, a novel method involving daily exposure to carbon monoxide (CO) has been proposed to amplify altitude training adaptations at suboptimal altitudes. Thirty-one male cyclists were assigned to three groups: Live-High and Train-High with CO inhalation (LHTH_CO), Live-High Train-High (LHTH), and Live-Low Train-Low (LLTL). The LHTH_CO group underwent CO inhalation twice daily in the afternoon/evening to elevate carboxyhemoglobin concentration to ⁓10%. Hematological variables, in-vivo muscle oxidative capacity, and physiological indicators of cycling performance were assessed before and after a 3-week altitude training camp at 2100 m.a.s.l. LHTH_CO demonstrated a larger increase in hemoglobin mass (Hb_mass) compared to both LHTH and LLTL. While there were no statistical differences between LHTH_CO and LHTH in submaximal and maximal performance measures, LHTH_CO displayed greater improvements in 1-min maximal power output during incremental testing (W_max), power output at lactate threshold, and maximal oxygen consumption (VO_2max) compared to LLTL. LHTH demonstrated a larger improvement than LLTL in W_max andVO_2maxwith no group differences in Hb_mass or submaximal measures. Muscle oxidative capacity did not differ between groups. These findings suggest that combining moderate altitude training with daily CO inhalation promotes hematological adaptations more effectively than moderate altitude alone and enhances cycling performance metrics in cyclists more than sea-level training.

The chemical digitalization of sweat using wearable sensing interfaces is an attractive alternative to traditional blood-based protocols in sports. Although sweat lactate has been claimed to be a relevant biomarker in sports, an analytically validated wearable system to prove that has not yet been developed. We present a fully integrated sweat lactate sensing system applicable to in situ perspiration analysis. The device can be conveniently worn in the skin to monitor real-time sweat lactate during sports, such as cycling and kayaking. The novelty of the system is threefold: advanced microfluidics design for sweat collection and analysis, an analytically validated lactate biosensor based on a rational design of an outer diffusion-limiting membrane, and an integrated circuit for signal processing with a custom smartphone application. The sensor covering the range expected for lactate in sweat (1-20 mM), with appropriate sensitivity (-12.5 ± 0.53 nA mM^-1), shows an acceptable response time (<90 s), and the influence of changes in pH, temperature, and flow rate are neglectable. Also, the sensor is analytically suitable with regard to reversibility, resilience, and reproducibility. The sensing device is validated through a relatively high number of on-body tests performed with elite athletes cycling and kayaking in controlled environments. Correlation outcomes between sweat lactate and other physiological indicators typically accessible in sports laboratories (blood lactate, perceived exhaustion, heart rate, blood glucose, respiratory quotient) are also presented and discussed in relation to the sport performance monitoring capability of continuous sweat lactate.

The present study investigated the effects of plyometric jump training on hard and soft surfaces on running economy (RE), maximal oxygen uptake (VO_2max), running performance and the rate of force development in orienteers. Nineteen orienteers (11 women and 8 men, body mass 61.1 ± 7.3 kg, age 21 ± 5.8 yrs) were randomly stratified based on sex, age, VO_2max and RE to plyometric jumping training (8 sessions over 4 weeks) on either a hard or a soft surface. RE, VO_2max and running performance were assessed on a treadmill and outdoor on- and off-trail loops. Moreover, ground reaction forces and force development were assessed during a one leg drop-jump test. The training intervention led to an overall 2-7% improvement in treadmill and off-trail RE, independent of the jumping surface and running velocity assessed. These improvements were not explained by force development during drop jump tests, which remained unchanged following the intervention. The changes in time-trial performance were associated with changes in RE. Plyometric training improved RE with no difference between the hard or the soft training surface and improved RE was also independent of the running speed assessed. Furthermore, improved running performance was associated with changes in RE after the intervention.