Is Maximal Lactate Accumulation Rate Promising for Improving 5000-m Prediction in Running?

Endurance running performance can be predicted by maximal oxygen uptake (V̇O2max), the fractional utilisation of oxygen uptake (%V̇O2max) and running economy at lactate threshold (REOBLA). This study aims to assess maximal lactate accumulation rate (cLamax) in terms of improving running performance prediction in trained athletes. Forty-four competitive female and male runners/triathletes performed an incremental step test, a 100-m sprint test and a ramp test to determine their metabolic profile. Stepwise linear regression was used to predict 5000-m time trial performance. Split times were recorded every 200-m to examine the 'finishing kick'. Females had a slower t5k and a lower V̇O2max, cLamax, 'finishing kick' and REOBLA. Augmenting Joyner's model by means of cLamax explained an additional 4.4% of variance in performance. When performing the same analysis exclusively for males, cLamax was not included. cLamax significantly correlated with %V̇O2max (r=-0.439, p=0.003) and the 'finishing kick' (r=0.389, p=0.010). cLamax allows for significant (yet minor) improvements in 5000-m performance prediction in a mixed-sex group. This margin of improvement might differ in middle-distance events. Due to the relationship to the 'finishing kick', cLamax might be related to individual pacing strategies, which should be assessed in future research.

Inefficient resource allocation is associated with reduced alpha activity in parietal regions in individuals with Parkinson's disease.

The brain's ability to act as an input filter and to suppress actions is crucial to navigate everyday life and impairments in these abilities affect quality of life substantially. Although Parkinson's disease (PD) is primarily known as a movement disorder, recent research has redefined it as a multisystem disorder affecting cognition, in particular inhibitory control and attentional resource allocation. Analysing the neural mechanisms underlying this cognitive deficit provides a better understanding of brain changes observed in patients affected by PD. Therefore, this study aimed to identify resource allocation to relevant and irrelevant stimuli in patients affected by PD. Besides neuropsychological tests, we employed electroencephalographic recordings during an auditory oddball paradigm in 13 patients suffering from idiopathic PD and 11 healthy controls (HC). Participants were instructed to ignore the standard stimulus and to respond as fast as possible to the rarely presented target tone. Event-related potentials (ERP) and time-frequency representations (TFR) were analyzed. Patients affected by PD showed faster response latencies to the task-irrelevant standard tones, but slower response latencies to target tones compared to HC. This observation was prominent at frontal sites during later P3-like processing stages. Reaction time, however, was prolonged in patients with PD, suggesting inefficient resource allocation. Additionally, TFR revealed reduced parietal alpha activity, which is associated with distractor suppression and functional inhibition in patients with PD compared to healthy controls. Thus, our results point towards inefficient resource allocation in patients with PD possibly driven by less functional inhibition through parietal alpha activity.

Maximal Lactate Accumulation Rate in All-out Exercise Differs between Cycling and Running.

This study aims to compare maximal lactate accumulation rate (V̇ Lamax) and power output (Pmax) between cycling and running in terms of reliability, differences between, and correlations among modalities. Eighteen competitive triathletes performed a 15-s all-out exercise test in cycling and a 100-m sprint test in running. Each test was performed twice and separated by one week. Exercise tests in cycling were performed on an ergometer whereas sprint tests in running were performed on an indoor track. Differences between trials and exercise modality were analyzed using two-way ANOVA. V̇ Lamax (ICC=0.894, ICC=0.868) and Pmax (ICC=0.907, ICC=0.965) attained 'good' to 'excellent' reliability in both cycling and running, respectively. V̇ Lamax was higher in running (d=0.709, p=0.016) whereas Pmax was lower in running (d=-0.862, p < 0.001). For V̇ Lamax, limits of agreement between modalities ranged from -0.224 to +0.437 mmol·l-1·s-1. Pmax correlated between modalities (r=0.811, p < 0.001), whereas no correlation was found in V̇ Lamax (r=0.418, p=0.084). V̇ Lamax is highly reliable in both modalities and higher in running compared to cycling. Since V̇ Lamax does not correlate between cycling and running, it should be determined sport-specifically.

Biomechanics of handcycling propulsion in a 30-min continuous load test at lactate threshold: Kinetics, kinematics, and muscular activity in able-bodied participants.

PURPOSE: This study aims to investigate the biomechanics of handcycling during a continuous load trial (CLT) to assess the mechanisms underlying fatigue in upper body exercise. METHODS: Twelve able-bodied triathletes performed a 30-min CLT at a power output corresponding to lactate threshold in a racing recumbent handcycle mounted on a stationary ergometer. During the CLT, ratings of perceived exertion (RPE), tangential crank kinetics, 3D joint kinematics, and muscular activity of ten muscles of the upper extremity and trunk were examined using motion capturing and surface electromyography. RESULTS: During the CLT, spontaneously chosen cadence and RPE increased, whereas crank torque decreased. Rotational work was higher during the pull phase. Peripheral RPE was higher compared to central RPE. Joint range of motion decreased for elbow-flexion and radial-duction. Integrated EMG (iEMG) increased in the forearm flexors, forearm extensors, and M. deltoideus (Pars spinalis). An earlier onset of activation was found for M. deltoideus (Pars clavicularis), M. pectoralis major, M. rectus abdominis, M. biceps brachii, and the forearm flexors. CONCLUSION: Fatigue-related alterations seem to apply analogously in handcycling and cycling. The most distal muscles are responsible for force transmission on the cranks and might thus suffer most from neuromuscular fatigue. The findings indicate that peripheral fatigue (at similar lactate values) is higher in handcycling compared to leg cycling, at least for inexperienced participants. An increase in cadence might delay peripheral fatigue by a reduced vascular occlusion. We assume that the gap between peripheral and central fatigue can be reduced by sport-specific endurance training.

Neurophysiological, neuropsychological, and cognitive effects of 30 days of isolation.

The increasing demand of space flights requires a profound knowledge of the chronologic reactions of the human body to extreme conditions. Prior studies already have shown the adverse effects of long-term isolation on psycho-physiological well-being. The chronology of the effects and whether short-term isolation periods already lead to similar effects has not been investigated. Therefore, the aim of the current study was to investigate the effects of short-term isolation (30 days) on mood, cognition, cortisol, neurotrophic factors, and brain activity. 16 participants were isolated in the Human Exploration Research Analog at NASA for 30 days. 17 non-isolated control participants were tested simultaneously. On mission days - 5, 7, 14, 28, and + 5, multiple tests including the Positive and Negative Affect Schedule-X and cognitive tests were conducted, and a 5-min resting electroencephalography was recorded. A fasted morning blood drawing was also done. Increased stress was observed via augmented cortisol levels during the isolation period. Activity within the parietal cortex was reduced over time, probably representing a neural adaptation to less external stimuli. Cognitive performance was not affected, but rather enhanced in both groups. No further significant changes in neurotrophic factors BDNF/IGF-1 and mood could be detected. These results suggest that 30 days of isolation do not have a significant impact on brain activity, neurotrophic factors, cognition, or mood, even though stress levels were significantly increased during isolation. Further studies need to address the question as to what extent increased levels of stress do not affect mental functions during isolation periods.

Lactate kinetics in handcycling under various exercise modalities and their relationship to performance measures in able-bodied participants.

PURPOSE: The aim of this study was to expand exercise testing in handcycling by (1) examining different approaches to determine lactate kinetics in handcycling under various exercise modalities and (2) identifying relationships between parameters of lactate kinetics and selected performance measures. METHODS: Twelve able-bodied nationally competitive triathletes performed a familiarisation, a sprint test, an incremental step test, and a continuous load trial at a power output corresponding to a lactate concentration (La) of 4 mmol l-1 (PO4) in a racing handcycle that was mounted on an ergometer. During the tests, La and heart rate (HR) were determined. As performance measures, maximal power output during the 15-s All-Out sprint test (POmax,AO15) and maximal power output during the incremental test (POmax,ST) were determined. As physiological parameters, coefficients of lactate kinetics, maximal lactate accumulation rate ([Formula: see text]Lamax), maximal La following the sprint test and incremental test (Lamax,AO15, Lamax,ST) and the increase in La within the last 20 min of the continuous trial (LaCrit,CT) were determined. RESULTS: Mean values of POmax,AO15 (545.6 ± 69.9 W), POmax,ST (131.3 ± 14.9 W), PO4 (86.73 ± 12.32 W), [Formula: see text]Lamax (0.45 ± 0.11 mmol l-1 s-1), Lamax,AO15 (6.64 ± 1.32 mmol l-1), Lamax,ST (9.64 ± 2.24 mmol l-1) and LaCrit,CT (0.74 ± 0.74 mmol l-1) were in accordance to literature. [Formula: see text]Lamax was positively correlated with Lamax,AO15 and POmax,AO15 and negatively correlated with POmax,ST. POmax,ST was negatively correlated with Lamax,AO15. PO4 was negatively correlated with Lamax,ST. CONCLUSIONS: [Formula: see text]Lamax was identified as a promising parameter for exercise testing in handcycling that can be supplemented by other parameters describing lactate kinetics following a sprint test.

Short-term isolation effects on the brain, cognitive performance, and sleep-The role of exercise.

Isolation is stressful and negatively affects sleep and mood and might also affect the structure and function of the brain. Physical exercise improves brain function. We investigated the influence of physical exercise during isolation on sleep, affect, and neurobehavioral function. N = 16 were isolated for 30 days with daily exercise routines (ISO100) and n = 16 isolated for 45 days with every second day exercise (ISO50). N = 27 were non-isolated controls who either exercised on a daily basis (CTRLEx) or refused exercise (CTRLNonEx) for 30 days. At the beginning and the end of each intervention, intravenous morning cortisol, melatonin, brain-derived neurotrophic factor and IGF-1, positive and negative affect scales, electroencephalography, cognitive function, and sleep patterns (actigraphy) were assessed. High levels of cortisol were observed for the isolated groups (p < .05) without negative effects on the brain, cognitive function, sleep, and mood after 4 to 6 weeks of isolation, where physical exercise was performed regularly. An increase in cortisol and impairments of sleep quality, mood, cognitive function, and neurotrophic factors (p < .05) were observed after 4 weeks of absence of physical exercise in the CTRLNonEx group. These findings raise the assumption that regular physical exercise routines are a key component during isolation to maintain brain health and function.

Case Report: Training Monitoring and Performance Development of a Triathlete With Spinal Cord Injury and Chronic Myeloid Leukemia During a Paralympic Cycle.

Introduction: Paratriathlon allows competition for athletes with various physical impairments. The wheelchair category stands out from other paratriathlon categories, since competing in swimming, handcycling, and wheelchair racing entails substantial demands on the upper extremity. Therefore, knowledge about exercise testing and training is needed to improve performance and avoid overuse injuries. We described the training monitoring and performance development throughout a Paralympic cycle of an elite triathlete with spinal cord injury (SCI) and a recent diagnosis of chronic myeloid leukemia (CML). Case Presentation/Methods: A 30-year-old wheelchair athlete with 10-years experience in wheelchair basketball contacted us for guidance regarding testing and training in paratriathlon. Laboratory and field tests were modified from protocols used for testing non-disabled athletes to examine their physical abilities. In handcycling, incremental tests were used to monitor performance development by means of lactate threshold (P OBLA) and define heart rate-based training zones. All-out sprint tests were applied to calculate maximal lactate accumulation rate ( V ˙ La max ) as a measure of glycolytic capabilities in all disciplines. From 2017 to 2020, training was monitored to quantify training load (TL) and training intensity distribution (TID). Results: From 2016 to 2019, the athlete was ranked within the top ten at the European and World Championships. From 2017 to 2019, annual TL increased from 414 to 604 h and demonstrated a shift in TID from 77-17-6% to 88-8-4%. In this period, P OBLA increased from 101 to 158 W and V ˙ La max decreased from 0.56 to 0.36 mmol·l-1·s-1. TL was highest during training camps. In 2020, after he received his CML diagnosis, TL, TID, and P OBLA were 317 h, 94-5-1%, and 108 W, respectively. Discussion: TL and TID demonstrated similar values when compared with previous studies in para-swimming and long-distance paratriathlon, respectively. In contrast, relative TL during training camps exceeded those described in the literature and was accompanied by physical stress. Increased volumes at low intensity are assumed to increase P OBLA and decrease V ˙ La max over time. CML treatment and side effects drastically decreased TL, intensity, and performance, which ultimately hindered a qualification for Tokyo 2020/21. In conclusion, there is a need for careful training prescription and monitoring in wheelchair triathletes to improve performance and avoid non-functional overreaching.

Disease-inclusive exercise classes improve physical fitness and reduce depressive symptoms in individuals with and without Parkinson's disease-A feasibility study.

BACKGROUND AND PURPOSE: Exercise is an adjunctive treatment in the management of Parkinson's disease (PD), but barriers such as health status, fear of overexertion, and lack of transportation to the location prevent regular exercise participation. Disease-inclusive exercise classes may offer an opportunity to make exercise more accessible for older adults with and without diseases. However, the efficacy of such heterogenous exercise classes is still widely unknown. Therefore, it was the aim of this study to analyze the feasibility of disease-inclusive exercise classes in older adults with and without PD. METHODS: Twenty-one older adults (healthy older adults (HOA): n = 13; PD: n = 8) completed an 8-week multimodal exercise intervention in supervised group sessions. Exercise classes lasted 60 min with the goal of two participations a week. We assessed physical fitness (timed up and go test [TUG], 6-minute walking test [6MWT], single leg stance), depressive symptoms and cognitive functions, and we determined growth factors (BDNF & IGF-1) before and after the intervention to determine the effects and by that, the feasibility of a disease-inclusive exercise program. Repeated measures ANOVA were used to establish changes. RESULTS: TUG and 6MWT improved significantly after the training in both HOA (p = .008; p < .001) and individuals with PD (p = .024; p < .001). Furthermore, individuals with PD increased single leg stance left (p = .003). HOA (p = .003) and individuals with PD (p = .001) decreased their depressive symptoms between pre- and post-test significantly. Whereas growth factors tended to improve, no differences in cognitive functions were revealed. CONCLUSION: Disease-inclusive multicomponent exercise improved physical functions and reduced depressive symptoms independent of health status. This should encourage exercise providers, researchers, and clinicians to further investigate disease-inclusive exercise, because they may have an important social impact and represent a more inclusive society.

Normalising surface EMG of ten upper-extremity muscles in handcycling: Manual resistance vs. sport-specific MVICs.

Muscular activity in terms of surface electromyography (sEMG) is usually normalised to maximal voluntary isometric contractions (MVICs). This study aims to compare two different MVIC-modes in handcycling and examine the effect of moving average window-size. Twelve able-bodied male competitive triathletes performed ten MVICs against manual resistance and four sport-specific trials against fixed cranks. sEMG of ten muscles [M. trapezius (TD); M. pectoralis major (PM); M. deltoideus, Pars clavicularis (DA); M. deltoideus, Pars spinalis (DP); M. biceps brachii (BB); M. triceps brachii (TB); forearm flexors (FC); forearm extensors (EC); M. latissimus dorsi (LD) and M. rectus abdominis (RA)] was recorded and filtered using moving average window-sizes of 150, 200, 250 and 300 ms. Sport-specific MVICs were higher compared to manual resistance for TB, DA, DP and LD, whereas FC, TD, BB and RA demonstrated lower values. PM and EC demonstrated no significant difference between MVIC-modes. Moving average window-size had no effect on MVIC outcomes. MVIC-mode should be taken into account when normalised sEMG data are illustrated in handcycling. Sport-specific MVICs seem to be suitable for some muscles (TB, DA, DP and LD), but should be augmented by MVICs against manual/mechanical resistance for FC, TD, BB and RA.

Advanced glycation end products in intervertebral discs and hip joint capsules: correlation with senile amyloid?

Advanced glycation end-products (AGEs) may be involved in either amyloidogenesis or complications related to amyloid. The incidence of AGE increases with age as does the prevalence of amyloid affecting the hip joint capsule and intervertebral discs. We hypothesized that AGEs may be involved in the pathology of these amyloidoses and investigated the spatial and temporal relationship between AGEs and amyloid of intervertebral discs and hip joint capsules. Using immunohistochemistry, AGEs were found in all 71 intervertebral discs and all 87 hip joint capsules. Amyloid was present in 59 (83%) intervertebral discs and 65 (75%) hip joint capsules. AGEs were found in the immediate vicinity of amyloid deposits in 104 of 253 (41%) investigated amyloid deposits of the intervertebral discs and 159 of 311 (51%) investigated amyloid deposits of the hip joint capsules. However, only rarely were AGEs demonstrated within amyloid deposits. No linear correlation was found between the amount of AGEs and the amount of amyloid deposited. As AGEs are more common than amyloid in intervertebral discs and hip joint capsules, it is conceivable to suggest that AGEs might be involved in the pathogenesis of amyloid at these anatomical sites. However, the amyloid proteins appear not to be modified and AGE modification is not a general characteristic of senile amyloidoses.