TY - JOUR A1 - Bittmann, Frank A1 - Dech, Silas A1 - Schaefer, Laura T1 - Another way to confuse motor control BT - manual technique supposed to shorten muscle spindles reduces the muscular holding stability in the sense of adaptive force in male soccer players JF - Brain Sciences N2 - Sensorimotor control can be impaired by slacked muscle spindles. This was shown for reflex responses and, recently, also for muscular stability in the sense of Adaptive Force (AF). The slack in muscle spindles was generated by contracting the lengthened muscle followed by passive shortening. AF was suggested to specifically reflect sensorimotor control since it requires tension-length control in adaptation to an increasing load. This study investigated AF parameters in reaction to another, manually performed slack procedure in a preselected sample (n = 13). The AF of 11 elbow and 12 hip flexors was assessed by an objectified manual muscle test (MMT) using a handheld device. Maximal isometric AF was significantly reduced after manual spindle technique vs. regular MMT. Muscle lengthening started at 64.93 & PLUSMN; 12.46% of maximal voluntary isometric contraction (MVIC). During regular MMT, muscle length could be maintained stable until 92.53 & PLUSMN; 10.12% of MVIC. Hence, muscular stability measured by AF was impaired after spindle manipulation. Force oscillations arose at a significantly lower level for regular vs. spindle. This supports the assumption that they are a prerequisite for stable adaptation. Reduced muscular stability in reaction to slack procedures is considered physiological since sensory information is misled. It is proposed to use slack procedures to test the functionality of the neuromuscular system, which is relevant for clinical practice. KW - maximal isometric Adaptive Force KW - holding capacity KW - muscle stability KW - muscle instability KW - neuromuscular functioning KW - neuromuscular control KW - motor control KW - muscle spindle KW - muscle physiology KW - regulatory physiology Y1 - 2023 U6 - https://doi.org/10.3390/brainsci13071105 SN - 2076-3425 VL - 13 IS - 7 PB - MDPI CY - Basel ER - TY - JOUR A1 - Schaefer, Laura A1 - Carnarius, Friederike A1 - Dech, Silas A1 - Bittmann, Frank T1 - Repeated measurements of Adaptive Force BT - maximal holding capacity differs from other maximal strength parameters and preliminary characteristics for non-professional strength vs. endurance athletes JF - Frontiers in physiology N2 - 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. KW - Adaptive Force KW - maximal isometric Adaptive Force KW - holding capacity KW - neuromuscular control KW - strength vs. endurance athletes KW - injury mechanisms KW - repeated adaptive isometric–eccentric muscle action KW - holding (HIMA) and pushing (PIMA) isometric muscle action Y1 - 2023 U6 - https://doi.org/10.3389/fphys.2023.1020954 SN - 1664-042X VL - 14 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Bittmann, Frank A1 - Dech, Silas A1 - Schaefer, Laura T1 - How to confuse motor control BT - passive muscle shortening after contraction in lengthened position reduces the muscular holding stability in the sense of adaptive force JF - Life : open access journal N2 - Adaptation to external forces relies on a well-functioning proprioceptive system including muscle spindle afferents. Muscle length and tension control in reaction to external forces is most important regarding the Adaptive Force (AF). This study investigated the effect of different procedures, which are assumed to influence the function of muscle spindles, on the AF. Elbow flexors of 12 healthy participants (n = 19 limbs) were assessed by an objectified manual muscle test (MMT) with different procedures: regular MMT, MMT after precontraction (self-estimated 20% MVIC) in lengthened position with passive return to test position (CL), and MMT after CL with a second precontraction in test position (CL-CT). During regular MMTs, muscles maintained their length up to 99.7% +/- 1.0% of the maximal AF (AF(max)). After CL, muscles started to lengthen at 53.0% +/- 22.5% of AF(max). For CL-CT, muscles were again able to maintain the static position up to 98.3% +/- 5.5% of AF(max). AFiso(max) differed highly significantly between CL vs. CL-CT and regular MMT. CL was assumed to generate a slack of muscle spindles, which led to a substantial reduction of the holding capacity. This was immediately erased by a precontraction in the test position. The results substantiate that muscle spindle sensitivity seems to play an important role for neuromuscular functioning and musculoskeletal stability. KW - maximal isometric Adaptive Force KW - holding capacity KW - muscle stability KW - neuromuscular functioning KW - neuromuscular control KW - motor control KW - muscle spindle KW - muscle physiology KW - regulatory physiology Y1 - 2023 U6 - https://doi.org/10.3390/life13040911 SN - 2075-1729 VL - 13 IS - 4 PB - MDPI CY - Basel ER - TY - GEN A1 - Schaefer, Laura A1 - Carnarius, Friederike A1 - Dech, Silas A1 - Bittmann, Frank T1 - Repeated measurements of Adaptive Force BT - Maximal holding capacity differs from other maximal strength parameters and preliminary characteristics for non-professional strength vs. endurance athletes T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 831 KW - Adaptive Force KW - maximal isometric Adaptive Force KW - holding capacity KW - neuromuscular control KW - strength vs. endurance athletes KW - injury mechanisms KW - repeated adaptive isometric–eccentric muscle action KW - holding (HIMA) and pushing (PIMA) isometric muscle action Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-588030 SN - 1866-8364 IS - 831 ER - TY - JOUR A1 - Schaefer, Laura A1 - Dech, Silas A1 - Wolff, Lara L. A1 - Bittmann, Frank T1 - Emotional Imagery Influences the Adaptive Force in Young Women BT - Unpleasant Imagery Reduces Instantaneously the Muscular Holding Capacity JF - Brain Sciences N2 - 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. KW - Adaptive Force KW - maximal isometric Adaptive Force KW - holding capability KW - neuromuscular adaptation KW - motor control KW - pleasant and unpleasant imagery KW - emotions KW - emotional imagery KW - manual muscle test Y1 - 2022 U6 - https://doi.org/10.3390/brainsci12101318 SN - 2076-3425 VL - 12 IS - 10 PB - MDPI CY - Basel, Schweiz ER - TY - GEN A1 - Schaefer, Laura A1 - Dech, Silas A1 - Wolff, Lara L. A1 - Bittmann, Frank T1 - Emotional Imagery Influences the Adaptive Force in Young Women BT - Unpleasant Imagery Reduces Instantaneously the Muscular Holding Capacity T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 816 KW - Adaptive Force KW - maximal isometric Adaptive Force KW - holding capability KW - neuromuscular adaptation KW - motor control KW - pleasant and unpleasant imagery KW - emotions KW - emotional imagery KW - manual muscle test Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-582014 SN - 1866-8364 IS - 816 ER -