Purpose: The aim was to compare mesocycles with progressively increasing workloads and varied training intensity distribution (TID), that is, high-intensity (HIGH, > 4 mmol·L⁻¹blood lactate), low-intensity (LOW, < 2 mmol·L⁻¹blood lactate) or a combination of HIGH and LOW (referred to as “polarized” [POL]) on 5000-m running time and key components of endurance performance in recreational runners.Methods: Forty-two runners (peak oxygen uptake (V˙O_2peak): 45.2 ± 5.8 mL·min⁻¹·kg⁻¹) were systematically parallelized to one of three groups performing a 4-wk mesocycle with equal TID (two to four training sessions) followed by a 3-wk mesocycle with increased weekly training impulse (i.e., 50% increase compared to the first 4-wk mesocycle) of either HIGH, LOW, or POL and 1 wk tapering. V˙O_2peak, velocity at lactate threshold and running economy were assessed at baseline (T₀), after 4 wk (T₁), 7 wk (T₂), and 8 wk (T₃).Results: The 5000-m time decreased in all groups from T₀to T₂and T₃. V˙O_2peakincreased from T₀to T₂and T₃(P< 0.03) with HIGH and from T₀to T₂(P= 0.02) in LOW and from T₀to T₃(P= 0.006) with POL. Running economy improved only from T₁to T₃and from T₂to T₃(P< 0.04) with LOW. An individual mean response analysis indicated a high number of responders (n= 13 of 16) in LOW, with less in HIGH (n= 6/13) and POL (n= 8/16).Conclusions: On a group level, HIGH, LOW, and POL improve 5000-m time and V˙O_2peak. Changes in running economy occurred only with LOW. Based on the individual response of recreational runners the relative risk of nonresponding is greater with HIGH and POL compared with LOW.

The aim was to examine certain aspects of circulatory, metabolic, hormonal, thermoregulatory, cognitive, and perceptual responses while sitting following a brief session of high-intensity interval exercise. Twelve students (five men; age, 22 ± 2 years) performed two trials involving either simply sitting for 180 min (SIT) or sitting for this same period with a 6-min session of high-intensity exercise after 60 min (SIT+HIIT). At T₀ (after 30 min of resting), T₁ (after a 20-min breakfast), T₂ (after sitting for 1 h), T₃ (immediately after the HIIT), T₄, T₅, T₆, and T₇ (30, 60, 90, and 120 min after the HIIT), circulatory, metabolic, hormonal, thermoregulatory, cognitive, and perceptual responses were assessed. The blood lactate concentration (at T₃–T₅), heart rate (at T₃–T₆), oxygen uptake (at T₃–T₇), respiratory exchange ratio, and sensations of heat (T₃–T₅), sweating (T₃, T₄) and odor (T₃), as well as perception of vigor (T₃–T₆), were higher and the respiratory exchange ratio (T₄–T₇) and mean body and skin temperatures (T₃) lower in the SIT+HIIT than the SIT trial. Levels of blood glucose and salivary cortisol, cerebral oxygenation, and feelings of anxiety/depression, fatigue or hostility, as well as the variables of cognitive function assessed by the Stroop test did not differ between SIT and SIT+HIIT. In conclusion, interruption of prolonged sitting with a 6-min session of HIIT induced more pronounced circulatory and metabolic responses and improved certain aspects of perception, without affecting selected hormonal, thermoregulatory or cognitive functions.

Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre‐ and post‐intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV‐based interventions reduced the amount of moderate‐ and/or high‐intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV‐based training. Peak oxygen uptake () and submaximal running parameters (eg, LT1, LT2) improved following both HRV‐based and predefined training, with no clear difference in the extent of improvement in . Submaximal running parameters tended to improve more following HRV‐based training. Research findings to date have been limited and inconsistent. Both HRV‐based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater.

Gavanda, S, Isenmann, E, Geisler, S, Faigenbaum, A, and Zinner, C. The effects of high-intensity functional training compared with traditional strength or endurance training on physical performance in adolescents: a randomized controlled trial. J Strength Cond Res 36(3): 624–632, 2022—High-intensity functional training (HIFT) integrates different modes of exercise into training sessions performed at a relatively high intensity. Although HIFT is becoming more popular in youth strength and conditioning programs, research comparing the effects of HIFT with traditional forms of training, such as strength training (ST) or endurance training (ET) in younger populations are limited. Therefore, the aim of this study was to compare the effects of HIFT with those of ST and ET on strength and endurance performance in adolescents. Fifty-two untrained adolescents ( JOURNAL/jscr/04.03/00124278-202203000-00005/5FFU1/v/2025-08-06T005545Z/r/image-tiff = 26; JOURNAL/jscr/04.03/00124278-202203000-00005/5FFU2/v/2025-08-06T005545Z/r/image-tiff = 26; 17.3 ± 1.0 years) were randomly assigned to a HIFT, ST, ET, or control group. The intervention groups trained twice a week for 6 weeks with a training duration of 60–75 minutes per session. Performance was assessed before and after the intervention with the countermovement jump (CMJ), 20-m sprint (20 m), 3-repetition maximum back squat (3RM), and Yo-Yo test. The HIFT group made significant improvements in all performance tests (CMJ, +28.5 ± 27.6%; p > 0.001; 20-m time, −3.9 ± 5.0%; p = 0.002; 3RM, +34.3 ± 23.3%; p > 0.001; Yo-Yo, +14.5 ± 15.2%; p = 0.003), whereas the ST group improved in CMJ (+38.3 ± 27.7%; p > 0.001), 3RM (+22.2 ± 11.2%; p > 0.001), and Yo-Yo (+12.2 ± 21.4%; p = 0.013) and the ET group improved in CMJ (+23.4 ± 29.9%; p = 0.001), 20-m time (−5.2 ± 4.6%; p > 0.001), and Yo-Yo (+30.7 ± 37.3%; p > 0.001). No significant differences between the groups were evident when the results were compared for sex. These results indicate that HIFT is an effective training method for eliciting multifaceted improvements in strength, power, and endurance measures as compared with ET or ST alone in untrained adolescents.

Purpose: Research dealing with ischemic preconditioning (IPC) has primarily focused on variables associated to endurance performance with little research about the acute responses of IPC on repeated multidirectional running sprint performance. Here we aimed to investigate the effects of IPC of the arms and the legs on repeated running sprint performance with changes-of-direction (COD) movements. Methods: Thirteen moderately-to-well-trained team-sport athletes (7 males; 6 females; age: 24 ± 2 years, size: 175 ± 8 cm, body mass: 67.9 ± 8.1 kg) performed 16 × 30 m all-out sprints (15 s rest) with multidirectional COD movements on a Speedcourt with IPC (3 × 5 min) of the legs (IPC_leg; 240 mm Hg) or of the arms (remote IPC: IPC_remote; 180–190 mm Hg) 45 min before the sprints and a control trial (CON; 20 mm Hg). Results: The mean (±SD) time for the 16 × 30 m multidirectional COD sprints was similar between IPC_leg (Mean t: 16.0 ± 1.8 s), IPC_remote (16.2 ± 1.7 s), and CON (16.0 ± 1.6 s; p = 0.50). No statistical differences in oxygen uptake (mean difference: 0%), heart rate (1.1%) nor muscle oxygen saturation of the vastus lateralis (4.7%) and biceps brachii (7.8%) between the three conditions were evident (all p > 0.05). Conclusions: IPC (3 × 5 min) of the legs (220 mm Hg) or arms (180–190 mm Hg; remote IPC) applied 45 min before 16 × 30 m repeated multidirectional running sprint exercise does not improve sprint performance, oxygen uptake, heart rate nor muscle oxygen saturation of the vastus lateralis muscle when compared to a control trial.

The aim of the study was to investigate the effects of wearing various levels of compression following repeated and exhausting sprint exercise on variables related to recovery. Twelve well‐trained handball players performed three sessions of repeated and exhausting sprint exercise (30 × 30m). Directly after each session the participants wore tights extending from below the hip to the foot with either 0, 10, or 25 mm Hg of compression onto the thigh and calf muscles. 48 h after the training session all participants performed 5 × 30m sprints and counter movement jumps. Before, directly after, 24 h, and 48 h after the training session venous blood samples were drawn for the determination of creatine kinase (CK), urea, C‐reactive protein (CRP). At the same time points, subjective ratings of the Acute Recovery and Stress Scale (ARSS) questionnaires were obtained. The results for plasma concentrations of CK and urea showed ‘likely’ to ‘very, very likely’ beneficial effects for compression garments exerting 10 mm Hg of compression (p = 0.06–1.0). With regard to sprint and jump performance no differences were evident between 0, 10, and 25 mm Hg (p = 0.07–1.0). In addition, subjective scores from the ARSS did not differ between conditions over time (p > 0.05). We conclude that the application of 10 mm Hg leg compression compared to 0 and 25 mm Hg of compression during 48 h of recovery from repeated and exhausting sprints lowered the plasma concentrations of CK and urea with no improvements in recovery for performance.