Anders Vinther

Exercise-induced rib stress fractures: potential risk factors related to thoracic muscle co-contraction and movement pattern

The etiology of exercise‐induced rib stress fractures (RSFs) in elite rowers is unclear. The purpose of the study was to investigate thoracic muscle activity, movement patterns and muscle strength in elite rowers. Electromyographic (EMG) and 2‐D video analysis were performed during ergometer rowing, and isokinetic muscle strength was measured in seven national team rowers with a history of RSF and seven matched controls (C).

Exercise‐induced rib stress fractures: influence of reduced bone mineral density

Exercise‐induced rib stress fractures have been reported frequently in elite rowers during the past decade. The etiology of rib stress fractures is unclear, but low bone mineral density (BMD) has been suggested to be a potential risk factor for stress fractures in weight‐bearing bones. The present study investigated BMD in seven Danish national team rowers with previous rib stress fracture (RSF) and 7 controls (C) matched for gender, age, height, weight and training experience. Total body scan and specific scans of the lumbar spine (L2–L4), femoral neck and distal radius were performed using a DEXA scanner. The RSF subjects showed significantly lower L2–L4 BMD: RSF: 1.22±0.05 g cm−2 (mean±SEM) (median 1.19 g cm−2, range 1.02–1.37 g cm−2) compared to C: 140±0.04 g cm−2 (median 1.41 g cm−2, range 1.27–1.57 g cm−2) (P=0.028).The present results suggest that low bone mineral density may be a potential risk factor for the development of exercise‐induced rib stress fractures in elite rowers.

Slide-based ergometer rowing: Effects on force production and neuromuscular activity.

Force production profile and neuromuscular activity during slide‐based and stationary ergometer rowing at standardized submaximal power output were compared in 14 male and 8 female National Team rowers. Surface electromyography (EMG) was obtained in selected thoracic and leg muscles along with synchronous measurement of handle force and rate of force development (RFD). Compared to stationary conditions, slide‐based peak force decreased by 76 (57–95) N (mean 95% CI) in males (P < 0.001) and 20 (8–31) N (P < 0.05) in females. Stroke rate increased (+10.7%) and late‐phase RFD decreased (−20.7%) in males (P < 0.05). Neuromuscular activity in m. vastus lateralis decreased in the initial drive phase from 59% to 51% of EMGmax in males and from 57% to 52% in females (P < 0.01–0.05), while also decreasing in the late recovery phase from 20% to 7% in males and 17% to 7% in females (P < 0.01). Peak force and maximal neuromuscular activity in the shoulder retractors always occurred in the second quartile of the drive phase. In conclusion, peak force and late‐phase RFD (males) decreased and stroke rate increased (males) during slide‐based compared to stationary ergometer rowing, potentially reducing the risk of overuse injury. Neuromuscular activity was more affected in leg muscles than thoracic muscles by slide‐based ergometer rowing.

Testosterone and BMD in elite male lightweight rowers

The purpose of the present study was to investigate if a relationship between BMD and testosterone levels could be identified in elite male lightweight rowers. Thirteen male lightweight national team rowers had their BMD measured in a DEXA scanner. Plasma concentrations of total testosterone (TT), free testosterone (FT), dihydrotestosterone (DHT) and sex hormone binding globulin (SHBG) and additional parameters related to bone metabolism were measured. Plasma concentrations of TT, FT and DHT were in the lower part of the normal range, while BMD was close to or above normal. BMD of total body and L2 - L4 were correlated to years of training (r (s): 0.59, p = 0.034 and r (s): 0.73, p = 0.005) and to TT (r (s): 0.56, p = 0.046 and rs: 0.63, p = 0.021). Moreover, L2 - L4 BMD was correlated to FT (r (s): 0.62, p = 0.024). After adjusting for years of training, partial correlation analysis showed a significant correlation between L2 - L4 BMD and TT (r (s): 0.61, p < 0.05). BMD appears to be influenced by both testosterone levels and years of training in elite male lightweight rowers. The relatively high BMD and low testosterone levels indicate that the mechanical loading induced by rowing is more important to BMD than testosterone levels. Prospective investigations are needed to elucidate potential causal relationships.

Progressive resistance training in head and neck cancer patients undergoing concomitant chemoradiotherapy

Patients with head and neck squamous cell carcinoma undergoing concomitant chemoradiotherapy (CCRT) frequently experience weight loss, especially loss of lean body mass (LBM), and reduced functional performance. This study investigated whether a 12‐week hospital‐based progressive resistance training (PRT) program during CCRT is feasible in the clinical setting before planning initiation of a larger randomized study which is the long‐term goal.

Differences in tendon properties in elite badminton players with or without patellar tendinopathy

The aim of this study was to examine the structural and mechanical properties of the patellar tendon in elite male badminton players with and without patellar tendinopathy. Seven players with unilateral patellar tendinopathy (PT group) on the lead extremity (used for forward lunge) and nine players with no current or previous patellar tendinopathy (CT group) were included. Magnetic resonance imaging was used to assess distal patellar tendon dimensions. Patellar tendon mechanical properties were assessed using simultaneous tendon force and deformation measurements. Distal tendon cross‐sectional area (CSA) normalized for body weight (mm2/kg2/3) was lower in the PT group compared with the CT group on both the non‐lead extremity (6.1 ± 0.3 vs 7.4 ± 0.2, P < 0.05) and the lead extremity (6.5 ± 0.6 vs 8.4 ± 0.3, P < 0.05). Distal tendon stress was higher in the PT group compared with the CT group for both the non‐lead extremity (31 ± 1 vs 27 ± 1 MPa, P < 0.05) and the lead extremity (32 ± 3 vs 21 ± 3 MPa, P < 0.01). Conclusively, the PT group had smaller distal patellar tendon CSA on both the injured (lead extremity) and the uninjured side (non‐lead extremity) compared with the CT group. Subsequently, the smaller CSA yielded a greater distal patellar tendon stress in the PT group. Therefore, a small tendon CSA may predispose to the development of tendinopathy.

Differences in tendon properties in elite badminton players with or without patellar tendinopathy: Mechanics of patellar tendinopathy

The aim of this study was to examine the structural and mechanical properties of the patellar tendon in elite male badminton players with and without patellar tendinopathy. Seven players with unilateral patellar tendinopathy (PT group) on the lead extremity (used for forward lunge) and nine players with no current or previous patellar tendinopathy (CT group) were included. Magnetic resonance imaging was used to assess distal patellar tendon dimensions. Patellar tendon mechanical properties were assessed using simultaneous tendon force and deformation measurements. Distal tendon cross‐sectional area (CSA) normalized for body weight (mm2/kg2/3) was lower in the PT group compared with the CT group on both the non‐lead extremity (6.1 ± 0.3 vs 7.4 ± 0.2, P < 0.05) and the lead extremity (6.5 ± 0.6 vs 8.4 ± 0.3, P < 0.05). Distal tendon stress was higher in the PT group compared with the CT group for both the non‐lead extremity (31 ± 1 vs 27 ± 1 MPa, P < 0.05) and the lead extremity (32 ± 3 vs 21 ± 3 MPa, P < 0.01). Conclusively, the PT group had smaller distal patellar tendon CSA on both the injured (lead extremity) and the uninjured side (non‐lead extremity) compared with the CT group. Subsequently, the smaller CSA yielded a greater distal patellar tendon stress in the PT group. Therefore, a small tendon CSA may predispose to the development of tendinopathy.