Running is a basic form of human locomotion and one of the most popular sports worldwide. While the leg biomechanics of running have been studied extensively, few studies have focused on upper-body movement. However, an effective arm swing and longitudinal rotation of the shoulders play an important role in running efficiency as they must compensate for the longitudinal torques generated by the legs. The aim of this study is to assess the upper-body rotation using wearable inertial sensors and to elucidate its relation to energy expenditure. Eighty-six junior elite middle- and long-distance runners (37 female, 49 male) performed an incremental treadmill test with sensors attached on both shoulders, tibiae and the sacrum. The mean and total horizontal shoulder and pelvis rotations per stride were derived while energy costs were determined using respiratory gas analysis and blood sampling. Results show that shoulder and pelvis rotations increase with running speed. While shoulder rotation is more pronounced in female than in male runners, there is no sex difference for pelvis rotation. The energy cost of running and upper trunk rotation prove to be slightly negatively correlated. In conclusion, upper body rotation appears to be an individual characteristic influenced by a sex-specific body mass distribution.

With Norway’s successes in middle and long-distance running, lactate-guided threshold training has regained importance in recent years. Therefore, the aim of the present study was to investigate the individual responses on common monitoring parameters based on a lactate-guided conventional training method. In total, 15 trained runners (10 males, 5 females; 18.6 ± 3.3 years; VO_2max: 59.3 ± 5.9 mL kg⁻¹ min⁻¹) completed a 40-min continuous running session at a fixed lactate threshold load of 2 mmol L⁻¹. Lactate (La), oxygen uptake (VO₂), heart rate (HR), and rating of perceived exertion (RPE) were recorded. The chosen workload led to lactate values of 2.85 ± 0.56 mmol L⁻¹ (range: 1.90–3.80), a percentage of VO_2max utilization (%VO_2max) of 79.2 ± 2.5% (range: 74.9–83.8), a percentage of HR_max utilization (%HR_max) of 92.2 ± 2.5% (range: 88.1–95.3), and an RPE of 6.1 ± 1.9 (range: 3–10) at the end of the running session. Thereby, the individual responses differed considerably. These results indicate that a conventional continuous training method based on a fixed lactate threshold can lead to different individual responses, potentially resulting in various physiological impacts. Moreover, correlation analyses suggest that athletes with higher lactate threshold performance levels must choose their intensity in continuous training methods more conservatively (lower percentage intensity based on a fixed threshold) to avoid eliciting excessively strong metabolic responses.

Lower body positive pressure treadmills (LBPPTs) as a strategy to reduce musculoskeletal load are becoming more common as part of sports conditioning, although the requisite physiological parameters are unclear. To elucidate their role, ten well-trained runners (30.2 ± 3.4 years; VO_2max: 60.3 ± 4.2 mL kg⁻¹ min⁻¹) ran at 70% of their individual velocity at VO_2max (vVO_2max) on a LBPPT at 80% body weight support (80% BW_Set) and 90% body weight support (90% BW_Set), at 0%, 2% and 7% incline. Oxygen consumption (VO₂), heart rate (HR) and blood lactate accumulation (LA) were monitored. It was found that an increase in incline led to increased VO₂ values of 6.8 ± 0.8 mL kg⁻¹ min⁻¹ (0% vs. 7%, p < 0.001) and 5.4 ± 0.8 mL kg⁻¹ min⁻¹ (2% vs. 7%, p < 0.001). Between 80% BW_Set and 90% BW_Set, there were VO₂ differences of 3.3 ± 0.2 mL kg⁻¹ min⁻¹ (p < 0.001). HR increased with incline by 12 ± 2 bpm (0% vs. 7%, p < 0.05) and 10 ± 2 bpm (2% vs. 7%, p < 0.05). From 80% BW_Set to 90% BW_Set, HR increases of 6 ± 1 bpm (p < 0.001) were observed. Additionally, LA values showed differences of 0.10 ± 0.02 mmol l⁻¹ between 80% BW_Set and 90% BW_Set. Those results suggest that on a LBPPT, a 2% incline (at 70% vVO_2max) is not yet sufficient to produce significant physiological changes in VO₂, HR and LA—as opposed to running on conventional treadmills, where significant changes are measured. However, a 7% incline increases VO₂ and HR significantly. Bringing together physiological and biomechanical factors from previous studies into this practical context, it appears that a 7% incline (at 80% BW_Set) may be used to keep VO₂ and HR load unchanged as compared to unsupported running, while biomechanical stress is substantially reduced.

Introduction: High intensity interval training for improving maximal oxygen consumption (VO_2max) is a fundamental component of specific preparation phases for middle- and long-distance runners. In this context, short intervals are very popular in practice. The aim of the present study was to determine whether increasing the intensity of short intervals around maximal aerobic speed (vVO_2max), compared to traditional long interval runs, leads to a greater time spent above 90% VO_2max.Methods: 12 highly trained middle distance runners (7 males, 5 females) completed two VO_2max sessions (4 × 3 min at 95% vVO_2max, recovery: 3 min at 50% vVO_2max vs. 24 × 30 s at 100% vVO_2max, recovery: 30 s at 55% vVO_2max) on the treadmill in randomized order. Spiroergometric data, lactate accumulation, heart rate (HR) and perceived exertion was determined. This allowed the recording of time above 90% VO_2max and time above 90% HR_max. To analyze differences between the interval sessions, the paired t-test respectively the Wilcoxon test, if data were not normally distributed, were applied.Results: The time spent above 90% VO_2max was significantly lower in the 30-s intervals, despite the higher intensity, compared to the 3-min session (201.3 ± 268.4 s vs. 327.9 ± 146.8 s, p = 0.05, r = 0.57). In contrast, the time spent above 90% HR_max was significantly higher for the 30-s intervals than for the 3-min intervals (820 ± 249 s vs. 545 ± 131 s, p < 0.001, d = 1.73). The blood lactate concentrations showed higher values in the 3-min session (9.69 ± 1.82 mmol/L) compared to the 30-s session (7.59 ± 2.01 mmol/L, p < 0.001, d = 2.34). There was no statistical difference in the rating of perceived exertion between the two sessions (30-s session: 6.5 ± 1.0 vs. 3-min session: 6.8 ± 1.2; p = 0.26).Discussion: The present study showed that intensified 30-s intervals were inferior to traditional 3-min intervals regarding the time spent above 90% VO_2max. Given the observation of an opposing trend in the time spent above 90% HR_max, this parameter should be interpreted with caution in traditional training settings.

Running is a basic form of human locomotion and one of the most popular sports worldwide. While the leg biomechanics of running have been studied extensively, few studies have focused on the upper-body movement. However, an effective arm swing and longitudinal rotation of the shoulders play an important role in running efficiency as they must compensate for the longitudinal torques generated by the legs. The aim of this study is to assess the upper-body rotation using wearable inertial sensors and to elucidate its relation to energy expenditure. Eighty-six junior elite middle and long-distance runners (37 female, 49 male) performed an incremental treadmill test with sensors attached on both shoulders, tibiae and the sacrum. Mean and total horizontal shoulder and pelvis rotation per stride were derived while energy costs were determined using respiratory gas analysis and blood sampling. Results show that shoulder and pelvis rotation increase with running speed. While shoulder rotation is more pronounced in female than in male runners, there is no sex difference for pelvis rotation. Energy cost of running and upper trunk rotation prove to be slightly negatively correlated. In conclusion, upper body rotation appears to be an individual characteristic influenced by a sex-specific body mass distribution.