@misc{SchaeferBittmann2023,
  author    = {Schaefer, Laura and Bittmann, Frank},
  title     = {The adaptive force as a potential biomechanical parameter in the recovery process of patients with long COVID},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {823},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-58518},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-585187},
  pages     = {25},
  year      = {2023},
  abstract  = {Long COVID patients show symptoms, such as fatigue, muscle weakness and pain. Adequate diagnostics are still lacking. Investigating muscle function might be a beneficial approach. The holding capacity (maximal isometric Adaptive Force; AFisomax) was previously suggested to be especially sensitive for impairments. This longitudinal, non-clinical study aimed to investigate the AF in long COVID patients and their recovery process. AF parameters of elbow and hip flexors were assessed in 17 patients at three time points (pre: long COVID state, post: immediately after first treatment, end: recovery) by an objectified manual muscle test. The tester applied an increasing force on the limb of the patient, who had to resist isometrically for as long as possible. The intensity of 13 common symptoms were queried. At pre, patients started to lengthen their muscles at ~50\% of the maximal AF (AFmax), which was then reached during eccentric motion, indicating unstable adaptation. At post and end, AFisomax increased significantly to ~99\% and 100\% of AFmax, respectively, reflecting stable adaptation. AFmax was statistically similar for all three time points. Symptom intensity decreased significantly from pre to end. The findings revealed a substantially impaired maximal holding capacity in long COVID patients, which returned to normal function with substantial health improvement. AFisomax might be a suitable sensitive functional parameter to assess long COVID patients and to support therapy process},
  language  = {en}
}
@misc{SchaeferCarnariusDechetal.2023,
  author    = {Schaefer, Laura and Carnarius, Friederike and Dech, Silas and Bittmann, Frank},
  title     = {Repeated measurements of Adaptive Force},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {831},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-58803},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-588030},
  pages     = {19},
  year      = {2023},
  abstract  = {The Adaptive Force (AF) reflects the neuromuscular capacity to adapt to external loads during holding muscle actions and is similar to motions in real life and sports. The maximal isometric AF (AFisomax) was considered to be the most relevant parameter and was assumed to have major importance regarding injury mechanisms and the development of musculoskeletal pain. The aim of this study was to investigate the behavior of different torque parameters over the course of 30 repeated maximal AF trials. In addition, maximal holding vs. maximal pushing isometric muscle actions were compared. A side consideration was the behavior of torques in the course of repeated AF actions when comparing strength and endurance athletes. The elbow flexors of n = 12 males (six strength/six endurance athletes, non-professionals) were measured 30 times (120 s rest) using a pneumatic device. Maximal voluntary isometric contraction (MVIC) was measured pre and post. MVIC, AFisomax, and AFmax (maximal torque of one AF measurement) were evaluated regarding different considerations and statistical tests. AFmax and AFisomax declined in the course of 30 trials [slope regression (mean ± standard deviation): AFmax = -0.323 ± 0.263; AFisomax = -0.45 ± 0.45]. The decline from start to end amounted to -12.8\% ± 8.3\% (p < 0.001) for AFmax and -25.41\% ± 26.40\% (p < 0.001) for AFisomax. AF parameters declined more in strength vs. endurance athletes. Thereby, strength athletes showed a rather stable decline for AFmax and a plateau formation for AFisomax after 15 trials. In contrast, endurance athletes reduced their AFmax, especially after the first five trials, and remained on a rather similar level for AFisomax. The maximum of AFisomax of all 30 trials amounted 67.67\% ± 13.60\% of MVIC (p < 0.001, n = 12), supporting the hypothesis of two types of isometric muscle action (holding vs. pushing). The findings provided the first data on the behavior of torque parameters after repeated isometric-eccentric actions and revealed further insights into neuromuscular control strategies. Additionally, they highlight the importance of investigating AF parameters in athletes based on the different behaviors compared to MVIC. This is assumed to be especially relevant regarding injury mechanisms.},
  language  = {en}
}
@misc{SchaeferDechWolffetal.2022,
  author    = {Schaefer, Laura and Dech, Silas and Wolff, Lara L. and Bittmann, Frank},
  title     = {Emotional Imagery Influences the Adaptive Force in Young Women},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe},
  number    = {816},
  issn      = {1866-8364},
  doi       = {10.25932/publishup-58201},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-582014},
  pages     = {23},
  year      = {2022},
  abstract  = {The link between emotions and motor function has been known for decades but is still not clarified. The Adaptive Force (AF) describes the neuromuscular capability to adapt to increasing forces and was suggested to be especially vulnerable to interfering inputs. This study investigated the influence of pleasant an unpleasant food imagery on the manually assessed AF of elbow and hip flexors objectified by a handheld device in 12 healthy women. The maximal isometric AF was significantly reduced during unpleasant vs. pleasant imagery and baseline (p < 0.001, dz = 0.98-1.61). During unpleasant imagery, muscle lengthening started at 59.00 ± 22.50\% of maximal AF, in contrast to baseline and pleasant imagery, during which the isometric position could be maintained mostly during the entire force increase up to ~97.90 ± 5.00\% of maximal AF. Healthy participants showed an immediately impaired holding function triggered by unpleasant imagery, presumably related to negative emotions. Hence, AF seems to be suitable to test instantaneously the effect of emotions on motor function. Since musculoskeletal complaints can result from muscular instability, the findings provide insights into the understanding of the causal chain of linked musculoskeletal pain and mental stress. A case example (current stress vs. positive imagery) suggests that the approach presented in this study might have future implications for psychomotor diagnostics and therapeutics.},
  language  = {en}
}