---
title: "Stride-length alters energy flow through the upper extremity in baseball pitching"
id: "plos-one-19-the-composition-of-energy-flow-in-the-upper-extremity-under-different-lower"
canonical_url: "https://medichelpline.com/clinical-feed/plos-one-19-the-composition-of-energy-flow-in-the-upper-extremity-under-different-lower"
content_type: "clinical_feed_article"
specialty: "General"
source_name: "PLOS ONE (Medicine)"
source_url: "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0361030"
published_at: "2026-10-23T14:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Stride-length alters energy flow through the upper extremity in baseball pitching
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/plos-one-19-the-composition-of-energy-flow-in-the-upper-extremity-under-different-lower
- **Specialty:** [General](https://medichelpline.com/clinical-feed/general.md)
- **Primary Source:** PLOS ONE (Medicine)
- **Source URL:** [Original Journal Publication](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0361030)
- **Published At:** 2026-10-23T14:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- The study reanalyzed an existing dataset to examine how upper-extremity **energy flow** varies across three stride-length conditions during baseball pitching: under-stride (US), normal-stride (NS), and over-stride (OS). - Twenty male college pitchers (mean age 19.9 years; height 173.2 cm; mass 71.8 kg) performed maximal-effort pitches under the three stride conditions; the authors analyzed mechanical energy of upper-extremity segments and joint energy flow between key events. - Mechanical energy in proximal segments at stride-foot contact increased with longer stride length, indicating altered input from lower extremities across conditions. - At maximum shoulder external rotation, the **mechanical energy** in distal segments was greater in the NS condition than in US or OS; this pattern matched observed differences in ball speed across conditions. - Energy flow into the upper arm through the **shoulder joint** during the late cocking phase was greater in NS than in US and OS, and similar condition patterns were recorded for energy transfer through the **elbow** and **wrist** and for ball speed. - No statistically significant ball-speed difference was reported between US and OS; yet the shoulder energy-flow composition (JFP and STP components) differed between those two conditions, suggesting different joint-level strategies can yield similar total input to the arm. - The authors suggest that variations in how the shoulder composes incoming energy—rather than gross energy magnitude to the torso—may explain observed ball-speed differences; the dataset and limitations were described in the source.
## Clinical Analysis & Structured Key Points
The composition of energy flow in the upper extremity under different lower extremity mechanics in baseball pitching | PLOS One Browse Subject Areas ? Click through the PLOS taxonomy to find articles in your field. For more information about PLOS Subject Areas, click here . Article Authors Metrics Comments Media Coverage Reader Comments Figures Figures Abstract Generating high ball speed is crucial for achieving competitive baseball pitching performance. The lower extremity mechanics play a key role in generating high ball speed during a baseball pitch. However, some previous studies have reported no significant difference in ball speeds despite differences in lower extremity mechanics, highlighting the need to examine how energy is transferred through the upper extremity to the ball under these conditions. This study examined how upper extremity energy flow differed across stride-length conditions in relation to the observed differences in ball speed. Twenty college baseball pitchers pitched with under-stride length (US) and over-stride length (OS) in addition to normal-stride length (NS). We analyzed the mechanical energy of the upper extremity segments at key events during pitching, and the energy flow through each joint between events. The mechanical energy in the proximal segments at the stride foot contact increased as the stride length extended. In contrast, the mechanical energy in the distal segments at maximum external rotation in the shoulder joint was greater in the NS than in the US and OS, consistent with ball speed differences. During this phase, the energy flow to the upper arm through the shoulder joint was greater in the NS than in the US and OS, and the same condition pattern was observed for energy transfer through the elbow and wrist joints and for ball speed. Additionally, although no statistically significant difference in ball speed was observed between the US and OS, the JFP and STP components of shoulder energy flow showed different condition patterns, suggesting that shoulder energy flow composition may differ even when no statistically significant difference is observed in total energy flow into the upper arm. Citation: Matsuda R, Hirano Y, Umakoshi J, Kimura A (2026) The composition of energy flow in the upper extremity under different lower extremity mechanics in baseball pitching. PLoS One 21(10): e0361030. https://doi.org/10.1371/journal.pone.0361030 Editor: Filipe Manuel Clemente, Instituto Politecnico de Viana do Castelo, PORTUGAL Received: May 11, 2026; Accepted: October 2, 2026; Published: October 23, 2026 Copyright: © 2026 Matsuda et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: All relevant data are within the manuscript and its Supporting Information files. Funding: The author(s) received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Introduction Generating high ball speed is crucial for achieving competitive baseball pitching performance. The pitcher first elevates the stride leg, moves forward toward home plate, plants the stride foot, and rapidly rotates the trunk to release the ball. This motion follows a proximal-to-distal sequence of whole-body movements commonly referred to as a kinetic chain, in which mechanical linkages between successive body segments transfer energy from proximal to distal segments. Numerous studies have focused on lower extremity movement [ 1 – 7 ] because lower extremities play a key role in generating and initiating energy flow in the kinetic chain during baseball pitching [ 8 , 9 ]. Stride length is a significant parameter in lower extremity mechanics for achieving high ball speed. Several cross-sectional studies indicated a significant correlation between the stride length and ball speed [ 10 , 11 ], and some suggested that the stride length can predict ball speed [ 12 , 13 ]. Collectively, these findings support an association between longer stride length and higher ball speed. However, some studies focusing on experimentally altered stride lengths did not support this finding [ 14 , 15 ]. Ramsey et al. (2014) showed that there was no significant difference in ball speed between the under-stride and over-stride lengths, despite the total body linear momentum in the throwing direction increasing with the over-stride length. They further showed that the under-stride length allowed for an increase in the rotational momentum in the transverse plane compared to that of the over-stride length [ 15 ]. These findings imply that altering stride length changes the pitching mechanics but results in no significant difference in ball speed. However, it is difficult to fully explain ball speed based on whole-body linear or rotational momentum in pitching, which involves a large number of degrees of freedom. Therefore, a more detailed mechanical perspective is required to understand why no significant difference in ball speed is generated despite changes in the stride length. Baseball pitching involves the transfer of mechanical energy through the kinetic chain toward the ball from an energetic perspective [ 16 , 17 ]. Therefore, investigating how energy is transferred to the hand, which releases the ball, may provide insight into why no significant difference in ball speed is achieved. In whole-body pitching, the lower and upper extremities play distinct roles within the kinetic chain. The lower extremities primarily generate mechanical energy [ 4 ], whereas the upper extremity mainly transfers energy to the distal segments [ 16 , 18 ]. Accordingly, two possible mechanisms may explain the generation of no significant difference in ball speed under different stride length conditions. One possibility is that energy generated by the lower extremities is transferred through the upper extremity in a similar manner across conditions. In contrast, differences in energy generation at the lower extremities may be compensated for by differences in energy transfer within the upper extremity, resulting in a comparable amount of energy ultimately delivered to the ball. Some studies investigated energy generation in the lower extremities across different stride length conditions. Previous studies have shown that altering stride length changes ground reaction force and energy generation in the lower extremities [ 19 , 20 ]. However, these changes do not necessarily result in differences in the amount of energy flow to the upper torso [ 19 ]. No significant difference in ball speed would be expected across different stride length conditions if energy transfer through the upper extremity is preserved. Interestingly, a previous study that examined three conditions, including the normal-stride length, reported that ball speed was higher at the normal-stride length than at the over-stride and under-stride lengths. Based on these results, it can be inferred that the manner of energy transfer at the upper extremity changes across stride length conditions and may play an important role in determining ball speed, although the amount of energy flowing to the upper torso is not significantly different. Some studies reported the importance of energy flow in the upper extremity for generating high ball speed in whole-body pitching mechanics [ 16 , 17 ]. These studies showed significant correlations between ball speed and energy flow at the shoulder, elbow, and wrist joints. However, the mechanisms of energy flow differ across these joints. The elbow and wrist joints generate little energy and transfer it, whereas the shoulder joint generates and transfers energy [ 16 , 21 ]. Therefore, Köhler and Witt (2023) suggested that the shoulder joint is the last joint adding energy into the arm in throwing movements. Accordingly, the two general possibilities described above can be examined by identifying where condition differences in energy flow emerge within the upper extremity. The first possibility is that the amount of energy flow to the arm through the shoulder joint is different, resulting in a different amount of energy being transferred to the ball through the elbow and wrist joints. The second possibility is that the amount of energy flow to the arm through the shoulder joint is similar, but the energy transfer through the elbow and wrist joints is different, leading to a different amount of energy ultimately delivered to the ball. However, no studies have investigated the energy flow at the upper extremity under no significant difference in energy flow to the upper torso, and it remains unclear which possibility is engaged during pitching. Investigating the energy flow at the upper extremity would enhance understanding of why different ball speeds are generated despite no significant difference in energy flow to the upper torso. Furthermore, this investigation may help explain the central question in baseball biomechanics, which is how pitchers achieve high ball speed. Therefore, the purpose of this study was to examine how upper extremity energy flow differed across stride length conditions in relation to the observed differences in ball speed. Previous findings showed no statistically significant differences in energy flow to the upper torso across stride-length conditions [ 19 ]. Accordingly, we hypothesized that altering stride length would influence energy flow within the upper extremity during pitching. Specifically, we expected that differences in stride length would be reflected either in the magnitude of energy flow to the upper arm through the shoulder joint or in the way energy is transferred through the distal joints, resulting in different ball speeds. Methods Data used in this study were obtained from a previously conducted experiment on baseball pitching under different stride length conditions [ 19 ]. The original study examined how altering stride length affects energy flow in the lower extremities, which primarily generate mechanical energy. In contrast, the present study reanalyzes the same dataset to investigate how energy is transferred through the upper extremity to the ball. Participants Participants were recruited between 01/04/2023 and 31/08/2023. A total of twenty male college baseball pitchers (age: 19.9 ± 1.1 years; body height: 173.2 ± 5.8 cm; body mass: 71.8 ± 6.4 kg) volunteered to participate in this study. All participants met the following criteria. 1) Participants were overarm or three-quarter-arm throwers, and not side-arm or underarm throwers. 2) Participants had no injuries. 3) Participants were able to pitch with maximal effort. Prior to participation, all individuals received a detailed explanation of this study’s procedures and provided written informed consent. The study protocol complied with the Declaration of Helsinki and was approved by the Ethical Committee of the Graduate School of Sports and Health Studies at Hosei University (approval number: 2022_26). All 20 participants and all trials included in the original study were retained in the present analysis, with no additional participant or trial exclusions. None of the upper-extremity energy-flow variables planned for analysis were omitted. The upper-extremity energy-flow analysis was planned before the results were examined. Because the present study was a planned secondary analysis of the complete dataset from the original experiment, the sample size was fixed at 20 participants, and no additional sample-size calculation was performed specifically for the upper-extremity outcomes. Apparatus The experiment was conducted using two indoor force plates (Custom FP, Bertec Inc., Ohio, USA) and was surrounded by 13 motion-capture cameras (VICON MX, Vicon Motion Systems, Ltd., Oxford, UK). A motion capture system was used to record the body and ball motion at a sampling rate of 250 Hz. A set of 47 reflective markers was attached to the skin over specific anatomical landmarks according to a previous study [ 16 ]. Three reflective markers were attached to the index fingertip, middle fingertip, and interphalangeal joint of the middle finger. Furthermore, four reflective markers were attached to the ball. The ground reaction force (GRF) data were recorded at 1,000 Hz by two force plates and synchronized with the motion capture system. The global coordinate system (GCS) was a right-handed orthogonal coordinate system defined in a previous study [ 19 ]. Experimental procedure The participants pitched fastballs toward a target zone located 16 m away to examine pitching under different stride lengths. Initially, the individuals pitched five fastballs to a target zone with maximal effort, after a comfortable warm-up. For each participant, the stride length for the normal-stride condition (NS) was defined as the average stride length observed in the three fastest of the five initial baseline pitches. These baseline pitches were used only to determine the target stride length and were not included in subsequent analysis of ball speed, mechanical energy, or energy flow. The stride length was defined as the distance between the center of the ankle joint of the pivot leg at the maximal stride knee height and that of the stride leg at the stride foot contact. Based on the individually determined NS, two additional stride length conditions were established. The under-stride (US) and over-stride (OS) conditions were created by reducing or increasing the NS by 20%, respectively [ 19 ]. Visual reference lines were drawn on the force plate to guide stride foot placement, allowing participants to consistently pitch under each stride length condition (US, NS, or OS). We ensured participants had unlimited time to familiarize themselves with each stride length condition before measuring each condition. The participants pitched fastballs in each stride length condition until we collected ten balls that reached the target zone. Stride length conditions were tested in a randomized order, and experimental sessions were separated by one-week intervals to minimize learning and fatigue effects. Data analysis Marker trajectories were filtered using a fourth-order zero-lag Butterworth low-pass filter [ 22 ]. The cutoff frequency was determined separately for each trial, marker, and coordinate according to a previously described procedure [ 23 ] and the resulting cutoff frequencies ranged from 6.2 to 20.3 Hz. The GRF data were filtered at 15 Hz to minimize artifacts in the computation of the joint moment [ 24 , 25 ] and subsequently resampled to 250 Hz using cubic spline interpolation to synchronize the marker data. A whole-body model was developed using 16 rigid segments. Each segment and joint coordinate system definition followed the coordinate system used in baseball pitching studies [ 16 , 19 ]. The inertial parameters for each segment were estimated according to the definition of a previous study [ 26 ]. Mechanical energy was computed for the upper torso, upper arm, forearm, hand, and ball, and normalized by body mass. Intersegmental energy flow was quantified using the work of the joint force power ( JFP ), the segment torque power ( STP ), and the joint power ( JP ), which is the sum of the JFP and STP , by integrating each phase as described below. These quantities were evaluated at the trunk, shoulder, elbow, and wrist joints. The positive work represents the energy inflow to the adjacent distal segment through each joint, whereas the negative work indicates the energy outflow from each adjacent distal segment. The pitching motion was separated into three phases based on three events as previously defined [ 3 ]. The stride phase was defined as the section between the maximal knee height (MKH) of the stride leg and the stride foot contact (SFC). The arm-cocking phase was between the SFC and the maximal external rotation (MER) of the throwing shoulder joint. The arm acceleration phase was between the MER and the ball release (REL). The SFC was defined as when the vertical GRF of the stride foot exceeded 5% of body mass [ 20 ]. The MER was identified as when reaching the maximum of humeral long-axis rotation relative to the thorax between SFC and REL, determined using a Z-Y’-Z” Euler rotation sequence. The REL was defined as when the distance between the center of the ball and the marker on the index fingertip exceeded 2 cm [ 27 ]. All data analyses were conducted using Python (version 3.11.7 for Windows). Statistical analysis For each biomechanical variable, all 10 pitches that reached the target zone were included in the analysis. The values obtained from these 10 pitches were averaged within each participant and stride length condition, and these mean values were used for statistical analysis ( S6 Table ). Group data are presented as means and standard deviations (SDs). Participant was specified as the subject factor in all repeated measures analyses. Two-way repeated measures analysis of variance (ANOVA) was conducted to examine the effects of condition and event on mechanical energy and the effects of condition and phase on work, respectively. The assumption of sphericity was assessed using Mauchly’s test. When sphericity was violated ( p < 0.05), Greenhouse–Geisser-adjusted degrees of freedom and p values were reported. A one-way repeated measures ANOVA was conducted to examine the effect of condition on ball speed. For the two-way repeated measures ANOVAs, when a significant condition × event or condition × phase interaction was observed, pairwise comparisons among stride length conditions were performed separately within each event or phase. For the one-way repeated measures ANOVA of ball speed, pairwise comparisons among stride length conditions were performed when a significant main effect of condition was observed. The p values and 95% confidence intervals (CIs) for the pairwise condition differences were adjusted using the Bonferroni correction. Partial eta squared ( η 2 ) was calculated to assess the effect size for main effects and interactions, where values of 0.01, 0.06, and 0.14 indicate small, medium, and large effects, respectively. Cohen’s d was calculated for post hoc pairwise comparisons, where values of 0.20, 0.50, and 0.80 indicate small, medium, and large effects, respectively. The significance level for all comparisons was p < 0.05. All statistical analyses were performed using Python (version 3.11.7 for Windows). Results Ball speeds obtained from the pitching trials analyzed in the present study have been reported previously [ 19 ]. The means and SDs of ball speed for the three stride-length conditions, together with the pairwise condition contrasts, are presented in Table 1 to provide context for the present upper extremity analysis. Ball speed was greater in the NS than in the US and OS, whereas no statistically significant difference was observed between the US and OS. These condition differences in ball speed provide the basis for examining how upper extremity energy flow differed among the stride length conditions. Download: PNG larger image TIFF original image Table 1. Ball speed across stride length conditions. https://doi.org/10.1371/journal.pone.0361030.t001 S1 Table shows the results of two-way repeated measures ANOVAs for the mechanical energy at each segment. There were no significant differences in the mechanical energy of all segments and the ball across the stride length condition at MKH ( Fig 1 and S2 Table ). However, differences in the segmental mechanical energy were observed between conditions at SFC. The mechanical energy of the upper torso, upper arm, and forearm increased as stride length extended ( Figs 1a – 1c , and S2 Table ). The mechanical energy of the hand was greater in the NS than in the US, whereas no statistically significant differences were observed between the NS an
## Related Clinical Research

- [Correction Notice: Photovoice-Greenspaces Health Protocol Republished After Error](https://medichelpline.com/clinical-feed/plos-one-3-correction-a-scoping-review-of-photovoice-studies-concerning-greenspaces-and.md)
- [Macular OCTA Signal and Lens Dislocation: Exploratory Comparison with Archived FBN1 Reports](https://medichelpline.com/clinical-feed/plos-one-11-lens-dislocation-octa-and-archived-fbn1-reports-an-exploratory-study.md)
- [How to define outcomes completely in clinical trials: six-element guidance](https://medichelpline.com/clinical-feed/plos-medicine-1-guidance-for-defining-outcomes-in-clinical-trials.md)
- [Major employers commit to faster, electronic prior authorizations for self-funded plans](https://medichelpline.com/clinical-feed/healthcare-dive-0-five-major-companies-pledge-faster-electronic-prior-authorizations.md)
- [Medicaid work requirements spark legal fights and implementation anxiety](https://medichelpline.com/clinical-feed/stat-news-5-anxiety-builds-over-medicaid-work-requirements.md)

## Navigation
- [← Back to General Feed](https://medichelpline.com/clinical-feed/general.md)
- [← All Clinical Specialties](https://medichelpline.com/clinical-feed.md)
## Medical & Regulatory Disclaimer

> [!CAUTION]
> MedicHelpline content is structured for research, educational, and professional discovery purposes. It does not constitute individual medical advice, clinical diagnosis, or treatment recommendations.
> Always verify dosing, contraindications, and regulatory alerts against official product labeling and primary regulatory sources before clinical decision-making.