The spectrum of Nb IV was observed with a sliding spark in the region from 430-3000 Å on the 6.5 m normal incidence vacuum spectrograph and the 3.4 m Jarrell-Ash spectrograph at the Zeeman-Laboratorium. About 294 lines were observed. The level system (ground configuration 4d2, isoelectronic with Sr I) was revised and extended to include 4d nl with nl = 4d, 5s, 5p, 5d, 4f, 6s and 6p respectively and 5s5p. Parametric calculations were made for the even and the odd level system taking into account the configuration interaction directly. The ionization energy was estimated to be 37.73 eV, from the position of the 4d5s and 4d6s configurations.

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PurposeThis study aimed to compare and rank gluteal muscle forces in eight hip-focused exercises performed with and without external resistance and describe the underlying fiber lengths, velocities, and muscle activations.MethodsMotion capture, ground reaction forces, and electromyography (EMG) were used as input to an EMG-informed neuromusculoskeletal model to estimate gluteus maximus, medius, and minimus muscle forces. Participants were 14 female footballers (18–32 yr old) with at least 3 months of lower limb strength training experience. Each participant performed eight hip-focused exercises (single-leg squat, split squat, single-leg Romanian deadlift [RDL], single-leg hip thrust, banded side step, hip hike, side plank, and side-lying leg raise) with and without 12 repetition maximum (RM) resistance. For each muscle, exercises were ranked by peak muscle force, and k-means clustering separated exercises into four tiers.ResultsThe tier 1 exercises for gluteus maximus were loaded split squat (95% confidence interval [CI] = 495–688 N), loaded single-leg RDL (95% CI = 500–655 N), and loaded single-leg hip thrust (95% CI = 505–640 N). The tier 1 exercises for gluteus medius were body weight side plank (95% CI = 338–483 N), loaded single-leg squat (95% CI = 278–422 N), and loaded single-leg RDL (95% CI = 283–405 N). The tier 1 exercises for gluteus minimus were loaded single-leg RDL (95% CI = 267–389 N) and body weight side plank (95% CI = 272–382 N). Peak gluteal muscle forces increased by 28–150 N when exercises were performed with 12RM external resistance compared with body weight only. Peak muscle force coincided with maximum fiber length for most exercises.ConclusionsGluteal muscle forces were exercise specific, and peak muscle forces increased by varying amounts when adding a 12RM external resistance. These findings may inform exercise selection by facilitating the targeting of individual gluteal muscles and optimization of mechanical loads to match performance, injury prevention, or rehabilitation training goals.

Background: People with femoroacetabular with femoroacetabular impingement syndrome (FAIS) often report pain during sports involving repeated sprinting. It remains unclear how sports participation influences running biomechanics in individuals with FAIS. Hypothesis: Changes in running biomechanics and/or isometric hip strength after repeated sprint exercise would be greatest in individuals with FAIS compared with asymptomatic individuals with (CAM) and without cam morphology (Control). Study Design: Controlled laboratory study. Level of Evidence: Level 3. Methods: Three-dimensional hip biomechanics during maximal running (10 m) and hip strength were measured in 49 recreationally active individuals (FAIS = 15; CAM = 16; Control = 18) before and after repeated sprint exercise performed on a nonmotorized treadmill (8-16 × 30 m). Effects of group and time were assessed for biomechanics and strength variables with repeated-measures analyses of variance. Relationships between hip pain (Copenhagen Hip and Groin Outcome Score) and changes in hip moments and strength after repeated sprint exercise were determined using Spearman’s correlation coefficients (ρ). Results: Running speed, hip flexion angles, hip flexion and extension moments, and hip strength in all muscle groups were significantly reduced from pre to post. No significant between-group differences were observed before or after repeated sprint exercise. No significant relationships (ρ = 0.04-0.30) were observed between hip pain and changes in hip moments or strength in the FAIS group. Conclusion: Changes in running biomechanics and strength after repeated sprint exercise did not differ between participants with FAIS and asymptomatic participants with and without cam morphology. Self-reported pain did not appear to influence biomechanics during running or strength after repeated sprint exercise in participants with FAIS. Clinical Relevance: A short bout of repeated sprinting may not elicit changes in running biomechanics in FAIS beyond what occurs in those without symptoms. Longer duration activities or activities requiring greater hip flexion angles may better provoke pathology-related changes in running biomechanics in people with FAIS.