Andreas Kramer

This study evaluated the reliability and sensitivity of a set of different common strength and power tests in a healthy adult population in a span of 9 weeks. Seventeen subjects (24.2 ± 2.2 years, 1.75 ± 0.10 m, 68.6 ± 14.2 kg, seven women) participated in the study. We tested countermovement jumps, reactive hops, and the maximal voluntary contraction (MVC) of handgrip and isometric knee extension. The tests were conducted in three separate sessions across a nine-week period, with one week between the first two sessions and eight weeks between the second and the third. Reliability and sensitivity statistics for each test were calculated for both the average of three trials and the best result during each session. The MVC of isometric knee extension and handgrip, as well as the countermovement jump test, demonstrated very high reliability and sensitivity over the nine-week period. The peak force of the reactive hops demonstrated high reliability but high sensitivity only for the average but not for the best result. The average contact time of reactive hops was neither a sensitive nor reliable measurement. In conclusion, isometric maximal knee extension and handgrip tests, as well as countermovement jumps and peak force of reactive hops, can be used as reliable and sensitive measurements of isometric and reactive strength and power over time periods of up to eight weeks. We recommend the use of the average results of three trials instead of the best performance value for longitudinal studies, as this procedure produces more consistent results and a lower measurement error.

This chapter considers the sporting theme in German Expressionism and Dada. It asks how and why German artists and writers associated with these movements embraced it, and how representations of sport were shaped by vitalist ideas about the sporting body. It also examines the extent to which such representations work in relation to each movement’s revitalising aesthetic, avant-garde techniques and broader cultural and political ambitions. To emphasise the continued presence of sporting themes in both movements while also considering similarities and differences between them, the chapter looks at visual representations of the sporting body in German Expressionism and Dada, and closely examines one particular sport, boxing, in the literature, art and manifestos of both movements. The chapter discusses work by Expressionists Paul Boldt, Rudolf Großmann, Max Pechstein, Heinrich Richter-Berlin, René Schickele and William Wauer, and Dadaists Erwin Blumenfeld, Max Ernst, George Grosz, John Heartfield and Hannah Höch.

Purpose: Spaceflight impairs physical capacity. Here we assessed the protective effect of artificial gravity (AG) on aerobic exercise capacity and muscle function during bed rest, a spaceflight analogue. Methods: 24 participants (33 ± 9 years, 175 ± 9 cm, 74 ± 10 kg, 8 women) were randomly allocated to one of three groups: continuous AG (cAG), intermittent AG (iAG) or control (CTRL). All participants were subjected to 60 days of six-degree head-down tilt bed rest, and subjects of the intervention groups completed 30 min of centrifugation per day: cAG continuously and iAG for 6 × 5 min, with an acceleration of 1g at the center of mass. Physical capacity was assessed before and after bed rest via maximal voluntary contractions, cycling spiroergometry, and countermovement jumps. Results: AG had no significant effect on aerobic exercise capacity, flexor muscle function and isometric knee extension strength or rate of force development (RFD). However, AG mitigated the effects of bed rest on jumping power (group * time interaction of the rmANOVA p < 0.001; iAG − 25%, cAG − 26%, CTRL − 33%), plantar flexion strength (group * time p = 0.003; iAG − 35%, cAG − 31%, CTRL − 48%) and plantar flexion RFD (group * time p = 0.020; iAG − 28%, cAG − 12%, CTRL − 40%). Women showed more pronounced losses than men in jumping power (p < 0.001) and knee extension strength (p = 0.010). Conclusion: The AG protocols were not suitable to maintain aerobic exercise capacity, probably due to the very low cardiorespiratory demand of this intervention. However, they mitigated some losses in muscle function, potentially due to the low-intensity muscle contractions during centrifugation used to avoid presyncope.

Exposure to the spaceflight environment results in profound multi-system physiological adaptations in which there appears to be substantial inter-individual variability (IV) between crewmembers. However, performance of countermeasure exercise renders it impossible to separate the effects of the spaceflight environment alone from those associated with exercise, whilst differences in exercise programs, spaceflight operations constraints, and environmental factors further complicate the interpretation of IV. In contrast, long-term head-down bed rest (HDBR) studies isolate (by means of a control group) the effects of mechanical unloading from those associated with countermeasures and control many of the factors that may contribute to IV. In this perspective, we review the available evidence of IV in response to the spaceflight environment and discuss factors that complicate its interpretation. We present individual data from two 60-d HDBR studies that demonstrate that, despite the highly standardized experimental conditions, marked quantitative differences still exist in the response of the cardiorespiratory and musculoskeletal systems between individuals. We also discuss the statistical concept of “true” and “false” individual differences and its potential application to HDBR data. We contend that it is currently not possible to evaluate IV in response to the spaceflight environment and countermeasure exercise. However, with highly standardized experimental conditions and the presence of a control group, HDBR is suitable for the investigation of IV in the physiological responses to gravitational unloading and countermeasures. Such investigations may provide valuable insights into the potential role of IV in adaptations to the spaceflight environment and the effectiveness of current and future countermeasures.

Bewegungsmangel ist Mitursache vieler Zivilisationskrankheiten und Zeitmangel ein häufiger Grund dafür. Im folgenden Beitrag wird ein kurzes, intensives Sprungtraining vorgestellt, das schon in der Weltraumforschung erfolgreich getestet wurde, sich ohne Zusatzgeräte in wenigen Minuten überall durchführen lässt und so problemlos in den Arbeitsalltag integriert werden kann.

Purpose: Long stays in space require countermeasures for the degrading effects of weightlessness on the human body, and artificial gravity (AG) has been proposed as an integrated countermeasure. The aim of this study was to assess the cardiorespiratory and neuromuscular demand of AG elicited via daily centrifugation during 60 days of bed rest. Methods: Twenty four participants (33 ± 9 y, 175 ± 9 cm, 74 ± 10 kg, 8 female) were subjected to 60 days of strict six-degree head-down tilt (HDT) bed rest and were randomly allocated to one of three experimental groups: 30 min of daily centrifugation with an acceleration of 1 g at the center of mass and 2 g at the feet applied continuously (cAG) or intermittently in 6 epochs of 5 min each, separated by 3 min breaks (iAG), or non-centrifuged control (CTRL). Cardiorespiratory demand during centrifugation was assessed at the beginning (HDT3) and end (HDT60) of the bed rest phase via spirometry and heart rate monitoring, leg muscle activation was monitored via electromyography. Results: On average, analyses of variance revealed that heart rate during centrifugation increased by 40% (iAG) and 60% (cAG) compared to resting values (p < 0.001), while oxygen uptake did not change significantly (p = 0.96). There was a preference for calf over knee extensor muscle activation (active time soleus 57 ± 27%, gastrocnemius medialis 45 ± 27% and vastus lateralis 27 ± 27%, p < 0.001), with large inter-individual differences in leg muscle active time. AG could not prevent the increase in resting heart rate after bed rest. For most of the recorded parameters, there were little differences between cAG and iAG, with the increase in heart rate during centrifugation being a notable exception (greater increase for cAG, p = 0.01). Conclusion: Daily 30 min bouts of artificial gravity elicited by centrifugation put a substantial demand on the heart as a pump without increasing oxygen consumption. If centrifugation is to be used as a countermeasure for the deteriorating effects of microgravity on physical performance, we recommend combining it with strenuous exercise.

Microgravity during long-term space flights induces degeneration of articular cartilage. Artificial gravity through centrifugation combined with exercise has been suggested as a potential countermeasure for musculoskeletal degeneration. The purpose of this study was to investigate the effect of different types of impact loading under normal and artificial gravity conditions on serum concentrations of cartilage oligomeric matrix protein (COMP), a biomarker of cartilage metabolism. Fifteen healthy male adults (26 ± 4 years, 181 ± 4 cm, 77 ± 6 kg) performed four different 30-min impact loading protocols on four experimental days: jumping with artificial gravity elicited by centrifugation in a short-arm centrifuge (AGJ), jumping with artificial gravity generated by low-pressure cylinders in a sledge jump system (SJS), vertical jumping under Earth gravity (EGJ), and running under Earth gravity (RUN). Five blood samples per protocol were taken: 30 min before, immediately before, immediately after, 30 min after, and 60 min after impact loading. Serum COMP concentrations were analyzed in these samples. During the impact exercises, ground reaction forces were recorded. Peak ground reaction forces were significantly different between the three jumping protocols (p < 0.001), increasing from AGJ (14 N/kg) to SJS (22 N/kg) to EGJ (29 N/kg) but were similar in RUN (22 N/kg) compared to SJS. The serum COMP concentration was increased (p < 0.001) immediately after all loading protocols, and then decreased (p < 0.001) at 30 min post-exercise compared to immediately after the exercise. Jumping and running under Earth gravity (EGJ and RUN) resulted in a significantly higher (p < 0.05) increase of serum COMP levels 30 min after impact loading compared to the impact loading under artificial gravity (RUN +30%, EGJ +20%, AGJ +17%, and SJS +13% compared to baseline). In conclusion, both the amplitude and the number of the impacts contribute to inducing higher COMP responses and are therefore likely important factors affecting cartilage metabolism. RUN had the largest effect on serum COMP concentration, presumably due to the high number of impacts, which was 10 times higher than for the jump modalities. Future studies should aim at establishing a dose-response relationship for different types of exercise using comparable amounts of impacts.

Life expectancy is steadily increasing in modern societies, and so are noncommunicable diseases such as cardiovascular diseases, diabetes, obesity, and cancer, accounting for more than 70% of all deaths globally. The costs associated with these diseases are enormous, but it has been estimated that the majority of these noncommunicable diseases are preventable. In addition to an unhealthy diet, tobacco use, and harmful use of alcohol, physical inactivity is a key risk factor. Consequently, physical activity is a logical remedy, and in this chapter an overview of the numerous beneficial effects of physical activity on health and performance is given. The chapter is divided into three parts: First, the basics of physical activity and exercise are discussed, for instance exercise classification, exercise intensity operationalization, energy supply, and the acute effects of exercise such as blood flow redistribution and increased cardiac output. In the second part, the effects of exercise on physical performance are summarized. Specifically, it is discussed how endurance, strength, power, and balance can be improved. This discussion includes recommendations regarding the type, intensity, and duration of the exercise leading to improvements in one of these aspects of physical performance, as well as the mechanisms causing these adaptations. In the third part, the beneficial effects of physical activity on physical and mental health are outlined, with particular attention to cardiovascular diseases, the metabolic syndrome, musculoskeletal diseases, mood, anxiety, depression, and dementia. It can be concluded that with adequate programming, regular physical activity is an effective way to improve physical performance, improve physical and mental health, and reduce the risk factors for many noncommunicable diseases such as cardiovascular diseases, metabolic syndrome, sarcopenia, osteoporosis, and depression. In contrast to medication, physical exercise has no negative side effects, costs very little, and targets many health issues at once. If the multitude of beneficial effects of regular exercise were to be combined in a single low-cost drug, it would be prescribed for almost all types of physical and mental health issues.

Humans are accustomed to Earth’s constant gravitational acceleration of 1g. Here we assessed if complex movements such as jumps can be adapted to different acceleration levels in a non-constant force field elicited through centrifugation. Kinematics, kinetics and muscle activity of 14 male subjects (age 27±5years, body mass 77±6kg, height 181±7cm) were recorded during repetitive hopping in a short-arm human centrifuge for five different acceleration levels (0.5g, 0.75g, 1g, 1.25g, 1.5g). These data were compared to those recorded during normal hops on the ground, and hops in a previously validated sledge jump system. Increasing acceleration from 0.5g to 1.5g resulted in increased peak ground reaction forces (+80%, p<0.001), rate of force development (+100%, p<0.001) and muscle activity (+30 to +140%, depending on phase, side and muscle). However, most of the recorded parameters did not attain the level observed for jumps on the ground or in the jump system. For instance, peak forces during centrifugation with 1g amounted to 60% of the peak forces during jumps on the ground, ground contact time was prolonged by 90%, and knee joint excursions were reduced by 50%. We conclude that in principle, a quick adaptation to acceleration levels other than the normal constant gravitational acceleration of 1g is possible, even in the presence of a non-constant force field and Coriolis forces. However, centrifugation introduced additional constraints compared to a constant force field without rotation, resulting in lower peak forces and changes in kinematics. These changes can be interpreted as a movement strategy aimed at reducing lower limb deflections caused by Coriolis forces.