TY - JOUR A1 - Sandau, Ingo A1 - Chaabene, Helmi A1 - Granacher, Urs T1 - Concurrent validity of barbell force measured from video-based barbell kinematics during the snatch in male elite weightlifters JF - PLOS ONE / Public Library of Science N2 - This study examined the concurrent validity of an inverse dynamic (force computed from barbell acceleration [reference method]) and a work-energy (force computed from work at the barbell [alternative method]) approach to measure the mean vertical barbell force during the snatch using kinematic data from video analysis. For this purpose, the acceleration phase of the snatch was analyzed in thirty male medal winners of the 2018 weightlifting World Championships (age: 25.2±3.1 years; body mass: 88.9±28.6 kg). Vertical barbell kinematics were measured using a custom-made 2D real-time video analysis software. Agreement between the two computational approaches was assessed using Bland-Altman analysis, Deming regression, and Pearson product-moment correlation. Further, principal component analysis in conjunction with multiple linear regression was used to assess whether individual differences related to the two approaches are due to the waveforms of the acceleration time-series data. Results indicated no mean difference (p > 0.05; d = −0.04) and an extremely large correlation (r = 0.99) between the two approaches. Despite the high agreement, the total error of individual differences was 8.2% (163.0 N). The individual differences can be explained by a multiple linear regression model (R2adj = 0.86) on principal component scores from the principal component analysis of vertical barbell acceleration time-series waveforms. Findings from this study indicate that the individual errors of force measures can be associated with the inverse dynamic approach. This approach uses vertical barbell acceleration data from video analysis that is prone to error. Therefore, it is recommended to use the work-energy approach to compute mean vertical barbell force as this approach did not rely on vertical barbell acceleration. KW - Acceleration KW - Linear regression analysis KW - Velocity KW - Principal component analysis KW - Kinematics KW - Motion KW - Scanning electron microscopy KW - Computer Software Y1 - 2021 U6 - https://doi.org/10.1371/journal.pone.0254705 SN - 1932-6203 VL - 16 IS - 7 PB - PLOS CY - San Francisco ER - TY - GEN A1 - Sandau, Ingo A1 - Chaabene, Helmi A1 - Granacher, Urs T1 - Concurrent validity of barbell force measured from video-based barbell kinematics during the snatch in male elite weightlifters T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe N2 - This study examined the concurrent validity of an inverse dynamic (force computed from barbell acceleration [reference method]) and a work-energy (force computed from work at the barbell [alternative method]) approach to measure the mean vertical barbell force during the snatch using kinematic data from video analysis. For this purpose, the acceleration phase of the snatch was analyzed in thirty male medal winners of the 2018 weightlifting World Championships (age: 25.2±3.1 years; body mass: 88.9±28.6 kg). Vertical barbell kinematics were measured using a custom-made 2D real-time video analysis software. Agreement between the two computational approaches was assessed using Bland-Altman analysis, Deming regression, and Pearson product-moment correlation. Further, principal component analysis in conjunction with multiple linear regression was used to assess whether individual differences related to the two approaches are due to the waveforms of the acceleration time-series data. Results indicated no mean difference (p > 0.05; d = −0.04) and an extremely large correlation (r = 0.99) between the two approaches. Despite the high agreement, the total error of individual differences was 8.2% (163.0 N). The individual differences can be explained by a multiple linear regression model (R2adj = 0.86) on principal component scores from the principal component analysis of vertical barbell acceleration time-series waveforms. Findings from this study indicate that the individual errors of force measures can be associated with the inverse dynamic approach. This approach uses vertical barbell acceleration data from video analysis that is prone to error. Therefore, it is recommended to use the work-energy approach to compute mean vertical barbell force as this approach did not rely on vertical barbell acceleration. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 716 KW - Acceleration KW - Linear regression analysis KW - Velocity KW - Principal component analysis KW - Kinematics KW - Motion KW - Scanning electron microscopy KW - Computer Software Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-521678 SN - 1866-8364 IS - 716 ER - TY - GEN A1 - Heß, Stefan A1 - Mousikou, Petroula A1 - Schroeder, Sascha T1 - Morphological processing in developmental handwriting production BT - Evidence from kinematics T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe N2 - In this study, we investigated effects of morphological processing on handwriting production in beginning writers of German. Children from Grades 3 and 4 were asked to copy words from a computer screen onto a pen tablet, while we recorded their handwriting with high spatiotemporal resolution. Words involved a syllable-congruent visual disruption (e.g., "Golfer"), a morpheme-congruent visual disruption (e.g., "Golfer"), or had no disruption (e.g., "Golfer"). We analyzed productions in terms of Writing Onset Duration and Letter Duration at the onset of the second syllable ("f" in "Gol.fer") and the onset of the suffix ("e" in "Golf_er"). Results showed that durations were longer at word-writing onset only for words with a morpheme-congruent visual disruption. Also, letter durations were longer at the onset of the second syllable (i.e., "-fer") and shorter at the onset of the suffix (i.e., "-er") only for words with a syllable-congruent visual disruption. We interpret these findings within extant theories of handwriting production and offer an explanation for the observed effects before and during trajectory formation. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 852 KW - Handwriting production KW - Spelling KW - Syllables KW - Morphemes KW - Kinematics Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-587363 SN - 0922-4777 SN - 1573-0905 IS - 4 ER - TY - JOUR A1 - Heß, Stefan A1 - Mousikou, Petroula A1 - Schroeder, Sascha T1 - Morphological processing in developmental handwriting production BT - Evidence from kinematics JF - Reading and writing: An interdisciplinary journal N2 - In this study, we investigated effects of morphological processing on handwriting production in beginning writers of German. Children from Grades 3 and 4 were asked to copy words from a computer screen onto a pen tablet, while we recorded their handwriting with high spatiotemporal resolution. Words involved a syllable-congruent visual disruption (e.g., "Golfer"), a morpheme-congruent visual disruption (e.g., "Golfer"), or had no disruption (e.g., "Golfer"). We analyzed productions in terms of Writing Onset Duration and Letter Duration at the onset of the second syllable ("f" in "Gol.fer") and the onset of the suffix ("e" in "Golf_er"). Results showed that durations were longer at word-writing onset only for words with a morpheme-congruent visual disruption. Also, letter durations were longer at the onset of the second syllable (i.e., "-fer") and shorter at the onset of the suffix (i.e., "-er") only for words with a syllable-congruent visual disruption. We interpret these findings within extant theories of handwriting production and offer an explanation for the observed effects before and during trajectory formation. KW - Handwriting production KW - Spelling KW - Syllables KW - Morphemes KW - Kinematics Y1 - 2021 U6 - https://doi.org/10.1007/s11145-021-10204-y SN - 1573-0905 SN - 0922-4777 VL - 35 IS - 4 SP - 899 EP - 917 PB - Springer CY - Dordrecht ER -