arXiv AI

When Does Exercise-Specific Joint Selection Help? An Audit of Evaluation and Control Design

The study audits the impact of exercise‑specific joint selection on skeleton‑based correctness classification using 1,057 repetitions from ten REHAB24‑6 subjects. It finds that the manual‑subset kNN gain varies from 0.055 for pooled out‑of‑fold AUROC to 0.020 for equal‑weight within‑person AUROC, with both intervals including zero. Across 1,000 dimension‑matched random maps, 14 match or exceed the manual pooled result, while 145 do so when bilateral structure and trunk inclusion are also matched; RBF‑SVM shows a positive within‑person gain, whereas logistic regression and a random‑convolution comparator show negative gains under that estimand.

arXiv Machine Learning
Sep 18

Intact-to-Amputee Transfer in Surface-EMG Gesture Decoding: Training Source and Calibration Budget

The study evaluates how well a surface‑EMG gesture recogniser trained on intact‑limb data transfers to transradial amputees. Zero‑shot transfer fails; the model needs a few labelled repetitions from the new user to outperform a per‑user classifier, achieving a macro‑F1 of 0.779 versus 0.589. Training on a larger pool of intact subjects, or combining intact and amputee data, yields the best cross‑population performance.

By Jethro Odeyemi, W. J. Zhang
arXiv Machine Learning
Sep 24

When Adaptation Hurts: Split Sensitivity and Person-Level Negative Transfer in Federated Wearable Onboarding

The paper evaluates six onboarding strategies for federated wearable models on five datasets using a leakage‑controlled protocol that fixes source checkpoints and separates calibration from evaluation. Results show that while average accuracy is high, person‑level performance can drop significantly, with some methods causing negative transfer for certain users. The study highlights that mean accuracy alone is insufficient and provides an auditable benchmark and failure map for future development.

By Rahil Aftab, Vineet Kumar Rakesh, Soumya Mazumdar, Tapas Samanta
arXiv Computer Vision
Sep 25

Training-Free Hold-Usage Detection in Sport Climbing with Foundation Pose Models

The paper presents a training‑free method for detecting which holds a climber uses in sport climbing videos by leveraging a frozen foundation pose model (Sapiens) that provides fingertip and toe keypoints. Using a simple proximity test, mutual exclusion, and a temporal‑persistence rule, the approach achieves high F_1 scores (up to 90.2%) on the Way Up dataset without any climbing‑specific training, outperforming repurposed pose pipelines. The resulting automatic predictions enable accurate coaching statistics, such as climb time and pace, with Pearson correlations of 1.00 and 0.94 respectively.

By Abu Bakar, Abdullah Aftab, Amir Hamza
arXiv Machine Learning
Sep 14

When Minute-Resolution Monitoring Meets Session-Level Injury Labels: Landmark-Based Discrimination in Elite Women's Football

The study introduces a framework that reconciles minute‑resolution athlete monitoring data with injury labels that are only available at the session level. By creating fixed‑time landmarks (10, 20, 30, 40, 50, and 60 minutes) and generating a single representation per athlete‑session up to each landmark, the authors evaluate several machine‑learning models and data‑augmentation strategies on elite women’s football data. Results show that discrimination varies across landmarks, with TabPFN outperforming Logistic Regression at later landmarks but not consistently beating Random Forest, and that synthetic augmentation offers benefits only in specific conditions.

By Evangelos Chatzidimitriou, Konstantinos Tserpes
arXiv Machine Learning
Sep 3

Orthogonal Ensembles and Tested Explanations for Performer-Independent Body-Motion Emotion Recognition

The paper investigates 12‑class body‑only emotion recognition from skeleton motion using a leave‑performer‑out evaluation, where chance accuracy is 8.3% and a reproduced STGCN++ baseline scores 25.73% Macro‑F1. By ensembling eleven models with orthogonal error modes, the authors achieve 36.80% Macro‑F1, a 43% relative improvement over the baseline. They also introduce a tested explanation suite that demonstrates the ensemble’s decisions rely on motion‑grounded body‑region evidence, aligning strongly with Laban Movement Analysis attributes rather than classical kinematics, while showing diffuse temporal saliency.

By Naoto Nishida, Yoshio Ishiguro
Hugging Face Trending Papers
Jul 26

Markerless Motion Capture in Routine Clinical Upper Limb Assessments: Validity and Insights Beyond Ordinal Scoring

The Action Research Arm Test (ARAT) is a widely-used upper limb outcome measure in neurorehabilitation, but its ordinal scoring is subjective and suffers from limited sensitivity and specificity. We evaluated whether artificial-intelligence (AI)-based markerless motion capture (MMC), embedded into ARAT assessments during clinical routine, accurately reconstructs upper limb movement and yields valid, objective kinematic metrics carrying clinically meaningful information beyond the ordinal score.

arXiv AI
Aug 24

Aggregate, Don't Adapt: Subject-Level Posterior Aggregation and Transductive Calibration for Cross-Site Parkinsonian Gait Severity

The paper reports the winning solution to the MoCha 2026 Parkinsonian Gait Benchmark, achieving a macro‑F1 score of 0.6945 on unseen clinical sites. The approach relies on a frozen public motion encoder followed by a single 4×512 linear layer, and gains are largely attributed to three key steps: exact replication of the benchmark’s head recipe, averaging per‑walk posteriors at the subject level, and a label‑free transductive calibration of feature means and decision thresholds. Extensive ablation studies show that fine‑tuning the encoder or using alternative encoders does not improve performance, and the subject‑level aggregation is identified as the primary contributor to the top score.

By Junlong Shen