Search

Knut Sindre Mølmen,* Sjur Johansen Øfsteng,* Bent R Rønnestad Section for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, Norway*These authors contributed equally to this workCorrespondence: Sjur Johansen ØfstengSection for Health and Exercise Physiology, Inland Norway University of Applied Sciences, Postbox 400, Elverum 2418, NorwayEmail sjur.johansen.ofsteng@inn.noBackground: Block periodization (BP) has been proposed as an alternative to traditional (TRAD) organization of the annual training plan for endurance athletes.Objective: To our knowledge, this is the first meta-analysis to evaluate the effect BP of endurance training on endurance performance and factors determinative for endurance performance in trained- to well-trained athletes.Methods: The PubMed, SPORTdiscus and Web of Science databases were searched from inception to August 2019. Studies were included if the following criteria were met: 1) the study examined a block-periodized endurance training intervention; 2) the study had a one-, two or multiple group-, crossover- or case-study design; 3) the study assessed at least one key endurance variable before and after the intervention period. A total of 2905 studies were screened, where 20 records met the eligibility criteria. Methodological quality for each study was assessed using the PEDro scale. Six studies were pooled to perform meta-analysis for maximal oxygen uptake (VO2max) and maximal power output (Wmax) during an incremental exercise test to exhaustion. Due to a lower number of studies and heterogenous measurements, other performance measures were systematically reviewed.Results: The meta-analyses revealed small favorable effects for BP compared to TRAD regarding changes in VO2max (standardized mean difference, 0.40; 95% CI=0.02, 0.79) and Wmax (standardized mean difference, 0.28; 95% CI=0.01, 0.54). For changes in endurance performance and workload at different exercise thresholds BP generally revealed moderate- to large-effect sizes compared to TRAD.Conclusion: BP is an adequate, alternative training strategy to TRAD as evidenced by superior training effects on VO2max and Wmax in athletes. The reviewed studies show promising effects for BP of endurance training; however, these results must be considered with some caution due to small studies with generally low methodological quality (mean PEDro score =3.7/10).Keywords: block training, traditional training, high-intensity training

The purpose of this study was to evaluate the effects of a microcycle of high-intensity interval training (HIT) sessions with multiple short work intervals followed by an active recovery period, compared to a similar duration of regular training, on determinants and indicators of endurance performance in well-trained cyclists. The participants in the BLOCK group performed a 6-day HIT microcycle including five HIT sessions (5 × 8.75-min 30/15 s short intervals) followed by a 6-day active recovery period with reduced training load, while the regular training group (REG) performed 12 days of their regular training, including four HIT sessions. Physiological testing was performed before and after the training periods. From pre- to post- intervention, BLOCK demonstrated significantly larger improvements than REG in mean power output (PO) during the last min of the maximal oxygen uptake (VO 2max ) test (PO VO2max ) (3.7 vs. 0.7%, p = 0.009, and effect size (ES) = 1.00) and mean PO during the 10-s sprint (2.8 vs. 1.9%, p = 0.028, and ES = 0.63). No significant differences between BLOCK and REG were observed for VO 2max , PO at 4 mmol·L -1 [blood lactate] (PO 4mmol ), 15-min maximal mean power output (PO 15-min ), and gross efficiency (p = 0.156-0.919). However, there was a tendency for larger improvements in the performance index (calculated from the main performance indicators PO VO2max , PO 4mmol , and PO 15-min ) in BLOCK compared to REG (2.9% vs. 1.2%, p = 0.079, and ES = 0.71). A 6-day high-intensity short-interval microcycle followed by a 6-day active recovery period induces improvements in endurance performance indicators compared to regular training, demonstrating its potential as an efficient strategy for endurance training in well-trained cyclists., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

It has been suggested that time spent at a high fraction of maximal oxygen consumption (% V ˙ $\dot{\mathrm{V}}$ O 2max ) plays a decisive role for adaptations to interval training. However, previous studies examining how interval sessions should be designed to achieve a high % V ˙ $\dot{\mathrm{V}}$ O 2max have exclusively been performed in males. The present study compared the % V ˙ $\dot{\mathrm{V}}$ O 2max attained during three different 6 × 8 min interval protocols, in female (n = 11; V ˙ $\dot{\mathrm{V}}$ O 2max , 62.5 (6.4) mL · min -1 ·kg -1 ) and male (n = 8; V ˙ $\dot{\mathrm{V}}$ O 2max , 81.0 (5.2) mL · min -1 ·kg -1 ) cyclists. Mean power output during work intervals were identical across the three interval protocols, corresponding to the cyclist's 40 min maximal effort (PO 40min ): (1) 30 s intervals at 118% of PO 40min interspersed with 15 s active recovery at 60% (30/15), (2) constant pace at 100% of PO 40min (CON), and (3) altering between 60 s intervals at 110% and 60 s at 90% of PO 40min (60/60). Additionally, the study explored whether the m. vastus lateralis characteristics of the cyclists (fiber type proportion, capillarization, and citrate synthase activity) were associated with the % V ˙ $\dot{\mathrm{V}}$ O 2max attained during the interval sessions. Overall, mean % V ˙ $\dot{\mathrm{V}}$ O 2max and time ≥90% of V ˙ $\dot{\mathrm{V}}$ O 2max were higher during 30/15 compared to CON (86.7 (10.1)% and 1123 (787) s versus 85.0 (10.4)% and 879 (779) s, respectively; both p ≤ 0.01) and 60/60 (85.6 (10.0)% and 917 (745) s, respectively; both p ≤ 0.05), while no difference was observed between 60/60 and CON (both p ≥ 0.36). During interval sessions, % V ˙ $\dot{\mathrm{V}}$ O 2max and time ≥90% of V ˙ $\dot{\mathrm{V}}$ O 2max did not differ between sexes. Skeletal muscle characteristics were not related to % V ˙ $\dot{\mathrm{V}}$ O 2max  during interval sessions. In conclusion, well-trained cyclists demonstrate highest % V ˙ $\dot{\mathrm{V}}$ O 2max during 30/15, irrespective of sex and skeletal muscle characteristics., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

It has been suggested that time at a high fraction (%) of maximal oxygen uptake (VO 2max ) plays a decisive role for adaptations to interval training. Yet, no study has, to date, measured the % of VO 2max during all interval sessions throughout a prolonged training intervention and subsequently related it to the magnitude of training adaptations. Thus, the present study aimed to investigate the relationship between % of VO 2max achieved during an interval training intervention and changes in endurance performance and its physiological determinants in well-trained cyclists. Twenty-two cyclists (VO 2max 67.1 (6.4) mL·min -1  ·kg -1 ; males, n = 19; females, n = 3) underwent a 9-week interval training intervention, consisting 21 sessions of 5 × 8-min intervals conducted at their 40-min highest sustainable mean power output (PO). Oxygen uptake was measured during all interval sessions, and the relationship between % of VO 2max during work intervals and training adaptations were investigated using linear regression. A performance index was calculated from several performance measures. With higher % of VO 2max during work intervals, greater improvements were observed for maximal PO during the VO 2max test (R 2 adjusted  = 0.44, p = 0.009), PO at 4 mmol·L -1 [blood lactate] (R 2 adjusted  = 0.25, p = 0.035), the performance index (R 2 adjusted  = 0.36, p = 0.013), and VO 2max (R 2 adjusted  = 0.54, p = 0.029). Other measures, such as % of maximal heart rate, were related to fewer outcome variables and exhibited poorer session-to-session repeatability compared to % of VO 2max . In conclusion, improvements in endurance measures were positively related to the % of VO 2max achieved during interval training. Percentage of VO 2max was the measure that best reflected the magnitude of training adaptations., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

Background: Changes in tryptophan metabolism through the kynurenine pathway (KP) are observed in several disorders and coupled with pathophysiological deviations., Methods: This study retrospectively compared the KP in serum in healthy subjects (108) with subjects with obesity (141), depression (49), and chronic obstructive pulmonary disease (COPD) (22) participating in four clinical studies and explored predictors of the changes in the KP metabolites., Results: Compared with the healthy group, the KP was upregulated in the disease groups with high kynurenine, quinolinic acid (QA), kynurenine/tryptophan-ratio and QA/xanthurenic acid-ratio and low kynurenic acid/QA-ratio. Tryptophan and xanthurenic acid were upregulated in the depressed group compared with the groups with obesity and COPD. The covariates BMI, smoking, diabetes, and C-reactive protein explained the significant differences between the healthy group and the group with obesity but not between the healthy group and the groups with depression and COPD, indicating that different pathophysiological conditions result in the same changes in the KP., Conclusions: The KP was significantly upregulated in the disease groups compared with the healthy group, and there were significant differences between the disease groups. Different pathophysiological abnormalities seemed to result in the same deviations in the KP.

Purpose: The aim of this study was to compare the effects of a 6-day high-intensity interval (HIT) block [BLOCK, n = 12, maximal oxygen uptake (V̇O 2max = 69. 6 ± 4.3 mL·min -1 ·kg -1 )] with a time-matched period with usual training (CON, n = 12, V̇O 2max = 69.2 ± 4.2 mL·min -1 ·kg -1 ) in well-trained cross-country (XC) skiers on physiological determinants and indicators of endurance performance. Furthermore, the study aimed to investigate the acute physiological responses, including time ≥90% of V̇O 2max , and its associated reliability during repeated HIT sessions in the HIT microcycle., Methods: Before the 6-day HIT block and following 5 days of recovery after the HIT block, both groups were tested on indicators of endurance performance. To quantify time ≥90% of V̇O 2max during interval sessions in the HIT block, V̇O 2 measurements were performed on the 1st, 2nd, and last HIT session in BLOCK., Results: BLOCK had a larger improvement than CON in maximal 1-min velocity achieved during the V̇O 2max test (3.1 ± 3.1% vs. 1.2 ± 1.6%, respectively; p = 0.010) and velocity corresponding to 4 mmol·L -1 blood lactate (3.2 ± 2.9% vs. 0.6 ± 2.1%, respectively; p = 0.024). During submaximal exercise, BLOCK displayed a larger reduction in respiratory exchange ratio, blood lactate concentration, heart rate, and rate of perceived exertion ( p < 0.05) and a tendency towards less energy expenditure compared to CON ( p = 0.073). The ICC of time ≥90% V̇O 2max in the present study was 0.57, which indicates moderate reliability., Conclusions: In well-trained XC skiers, BLOCK induced superior changes in indicators of endurance performance compared with CON, while time ≥90% of V̇O 2max during the HIT sessions in the 6-day block had a moderate reliability., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Rønnestad, Bjerkrheim, Hansen and Mølmen.)

Background: Subjects with chronic obstructive pulmonary disease (COPD) are prone to accelerated decay of muscle strength and mass with advancing age. This is believed to be driven by disease-inherent systemic pathophysiologies, which are also assumed to drive muscle cells into a state of anabolic resistance, leading to impaired abilities to adapt to resistance exercise training. Currently, this phenomenon remains largely unstudied. In this study, we aimed to investigate the assumed negative effects of COPD for health- and muscle-related responsiveness to resistance training using a healthy control-based translational approach., Methods: Subjects with COPD (n = 20, GOLD II-III, FEV 1predicted 57 ± 11%, age 69 ± 5) and healthy controls (Healthy, n = 58, FEV 1predicted 112 ± 16%, age 67 ± 4) conducted identical whole-body resistance training interventions for 13 weeks, consisting of two weekly supervised training sessions. Leg exercises were performed unilaterally, with one leg conducting high-load training (10RM) and the contralateral leg conducting low-load training (30RM). Measurements included muscle strength (n variables  = 7), endurance performance (n variables  = 6), muscle mass (n variables  = 3), muscle quality, muscle biology (m. vastus lateralis; muscle fiber characteristics, RNA content including transcriptome) and health variables (body composition, blood). For core outcome domains, weighted combined factors were calculated from the range of singular assessments., Results: COPD displayed well-known pathophysiologies at baseline, including elevated levels of systemic low-grade inflammation ([c-reactive protein] serum ), reduced muscle mass and functionality, and muscle biological aberrancies. Despite this, resistance training led to improved lower-limb muscle strength (15 ± 8%), muscle mass (7 ± 5%), muscle quality (8 ± 8%) and lower-limb/whole-body endurance performance (26 ± 12%/8 ± 9%) in COPD, resembling or exceeding responses in Healthy, measured in both relative and numeric change terms. Within the COPD cluster, lower FEV 1predicted was associated with larger numeric and relative increases in muscle mass and superior relative improvements in maximal muscle strength. This was accompanied by similar changes in hallmarks of muscle biology such as rRNA-content↑, muscle fiber cross-sectional area↑, type IIX proportions↓, and changes in mRNA transcriptomics. Neither of the core outcome domains were differentially affected by resistance training load., Conclusions: COPD showed hitherto largely unrecognized responsiveness to resistance training, rejecting the notion of disease-related impairments and rather advocating such training as a potent measure to relieve pathophysiologies., Trial Registration: ClinicalTrials.gov ID: NCT02598830. Registered November 6th 2015, https://clinicaltrials.gov/ct2/show/NCT02598830.

Background: Lifestyle therapy with resistance training is a potent measure to counteract age-related loss in muscle strength and mass. Unfortunately, many individuals fail to respond in the expected manner. This phenomenon is particularly common among older adults and those with chronic diseases (e.g. chronic obstructive pulmonary disease, COPD) and may involve endocrine variables such as vitamin D. At present, the effects of vitamin D supplementation on responses to resistance training remain largely unexplored., Methods: Ninety-five male and female participants (healthy, n = 71; COPD, n = 24; age 68 ± 5 years) were randomly assigned to receive either vitamin D 3 or placebo supplementation for 28 weeks in a double-blinded manner (latitude 61°N, September-May). Seventy-eight participants completed the RCT, which was initiated by 12 weeks of supplementation-only (two weeks with 10 000 IU/day, followed by 2000 IU/day), followed by 13 weeks of combined supplementation (2000 IU/day) and supervised whole-body resistance training (twice weekly), interspersed with testing and measurements. Outcome measures included multiple assessments of muscle strength (n variables  = 7), endurance performance (n = 6), and muscle mass (n = 3, legs, primary), as well as muscle quality (legs), muscle biology (m. vastus lateralis; muscle fibre characteristics, transcriptome), and health-related variables (e.g. visceral fat mass and blood lipid profile). For main outcome domains such as muscle strength and muscle mass, weighted combined factors were calculated from the range of singular assessments., Results: Overall, 13 weeks of resistance training increased muscle strength (13% ± 8%), muscle mass (9% ± 8%), and endurance performance (one-legged, 23% ± 15%; whole-body, 8% ± 7%), assessed as weighted combined factors, and were associated with changes in health variables (e.g. visceral fat, -6% ± 21%; [LDL] serum , -4% ± 14%) and muscle tissue characteristics such as fibre type proportions (e.g. IIX, -3% points), myonuclei per fibre (30% ± 65%), total RNA/rRNA abundances (15%/6-19%), and transcriptome profiles (e.g. 312 differentially expressed genes). Vitamin D 3 supplementation did not affect training-associated changes for any of the main outcome domains, despite robust increases in [25(OH)D] serum (∆49% vs. placebo). No conditional effects were observed for COPD vs. healthy or pre-RCT [25(OH)D] serum . In secondary analyses, vitamin D 3 affected expression of gene sets involved in vascular functions in muscle tissue and strength gains in participants with high fat mass, which advocates further study., Conclusions: Vitamin D 3 supplementation did not affect muscular responses to resistance training in older adults with or without COPD., (© 2021 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders.)