Jan-Peter Goldmann

The potential of toe flexor muscles to enhance performance

Abstract The metatarsal phalangeal joint (MPJ) and its crossing toe flexor muscles (TFM) represent the link between the large energy generating leg extensor muscles and the ground. The purpose of this study was to examine the functional adaptability of TFM to increased mechanical stimuli and the effects on walking, running and jumping performance. Fifteen men performed a heavy resistance TFM strength training with 90% of the maximal voluntary isometric contraction (MVIC) for 7 weeks (560 contractions) for the left and right foot. Maximal MPJ and ankle plantar flexion moments during MVICs were measured in dynamometers before and after the intervention. Motion analyses (inverse dynamics) were performed during barefoot walking, running, and vertical and horizontal jumping. Athletic performance was determined by measuring jump height and distance. Left (0.21 to 0.38 Nm · kg−1; P < 0.001) and right (0.24 to 0.40 Nm · kg−1; P < 0.001) MPJ plantar flexion moments in the dynamometer, external MPJ dorsiflexion moments (0.69 to 0.75 Nm · kg−1; P = 0.012) and jump distance (2.25 to 2.31 m; P = 0.006) in horizontal jumping increased significantly. TFM responded highly to increased loading within a few weeks. The increased force potential made a contribution to an athletes performance enhancement.

The potential of human toe flexor muscles to produce force

The maximal force a muscle produces depends among others on the length of the muscle and therefore on the positions of the joints the muscle crosses. Long and short toe flexor muscles (TFM) cross the ankle joints and metatarsal phalangeal joints (MPJ) and work against gravity during human locomotion. The purpose of this study was to describe the maximal moments around the MPJ during maximal voluntary isometric contractions (MVIC) of the TFM as a function of ankle joint and MPJ position. Twenty men performed MVIC of the TFM in a custom‐made dynamometer. Ankle and MPJ angles were modified after each contraction. External moments of force around the MPJ were determined. Moments ranged between 6.3 ± 2.6 Nm and 14.2 ± 5.8 Nm. Highest moments were produced at 0°–10° ankle joint dorsal flexion and 25°–45° MPJ dorsal flexion. Lowest moments were generated at 35° ankle joint plantar flexion and 0° MPJ dorsal flexion. In conclusion, if the ankle is plantar‐flexed, dorsal flexion of the MPJ avoids a disadvantage of the force–length relationship of TFM. Therefore, MPJ dorsal flexion is a necessary function in the push‐off phase of human locomotion to work against the loss of the mechanical output at the forefoot caused by plantar flexion of the ankle.

The gearing function of running shoe longitudinal bending stiffness

The purpose of the present study was to investigate whether altered longitudinal bending stiffness (LBS) levels of the midsole of a running shoe lead to a systematic change in lower extremity joint lever arms of the ground reaction force (GRF). Joint moments and GRF lever arms in the sagittal plane were determined from 19 male subjects running at 3.5 m/s using inverse dynamics procedures. LBS was manipulated using carbon fiber insoles of 1.9 mm and 3.2 mm thickness. Increasing LBS led to a significant shift of joint lever arms to a more anterior position. Effects were more pronounced at distal joints. Ankle joint moments were not significantly increased in the presence of higher GRF lever arms when averaged over all subjects. Still, two individual strategies (1: increase ankle joint moments while keeping push-off times almost constant, 2: decrease ankle joint moments and increase push-off times) could be identified in response to increased ankle joint lever arms that might reflect individual differences between subjects with respect to strength capacities or anthropometric characteristics. The results of the present study indicate that LBS systematically influences GRF lever arms of lower extremity joints during the push-off phase in running. Further, individual responses to altered LBS levels could be identified that could aid in finding optimum LBS values for a given individual.

Lower leg musculoskeletal geometry and sprint performance

The purpose of this study was to investigate whether sprint performance is related to lower leg musculoskeletal geometry within a homogeneous group of highly trained 100-m sprinters. Using a cluster analysis, eighteen male sprinters were divided into two groups based on their personal best (fast: N=11, 10.30±0.07s; slow: N=7, 10.70±0.08s). Calf muscular fascicle arrangement and Achilles tendon moment arms (calculated by the gradient of tendon excursion versus ankle joint angle) were analyzed for each athlete using ultrasonography. Achilles tendon moment arm, foot and ankle skeletal geometry, fascicle arrangement as well as the ratio of fascicle length to Achilles tendon moment arm showed no significant (p>0.05) correlation with sprint performance, nor were there any differences in the analyzed musculoskeletal parameters between the fast and slow sprinter group. Our findings provide evidence that differences in sprint ability in world-class athletes are not a result of differences in the geometrical design of the lower leg even when considering both skeletal and muscular components.

Athletic training with minimal footwear strengthens toe flexor muscles

During the propulsive phase of human locomotion, long and short toe flexor muscles (TFM) are exposed to mechanical stimuli caused by ground reaction forces. Further, flexible footwear seems to facilitate increased loading on foot structures. The purpose of the study was to evaluate the effects of high intensity athletic training with minimal footwear on TFM strength. Forty-seven female sport students participated and were randomly divided in three groups: the experimental group (EG; n = 18; 25 ± 5 yrs, 59 ± 6 kg) and the training control group (TG; n = 18; 23 ± 2 yrs, 64 ± 6 kg) performed high intensity athletic training (3 weeks, 5 times per week, 30 min per session) on the forefoot. The EG wore a minimal shoe, the TG performed the exercises with traditional training shoes. The basic control group (CG; n = 11; 27 ± 5 yrs, 63 ± 7 kg) participated in no training programme. To evaluate the training effects on TFM strength, maximum metatarsal phalangeal joint (MPJ) plantar flexion moments during maximal voluntary isometric contractions (MVIC) at 0° and 25° MPJ dorsal flexion were measured in a custom made dynamometer before and after the training intervention. The results showed that (1) in 0° MPJ dorsal flexion, MPJ moments were significantly increased in the EG (p < 0.01) and TG (p < 0.05) and differed significantly to the CG (p < 0.05); (2) in 25° MPJ dorsal flexion, TFM strength was significantly increased in the EG (p < 0.01), but not in the TG and CG (p > 0.05). In this joint angle position the EG significantly differed from the TG and CG (p < 0.05). The results of the study show that athletic exercises with minimal footwear strengthen TFM after three weeks intensive training.

Sprint start kinetics of amputee and non-amputee sprinters

The purpose of this study was to explore the relationship between the forces applied to the starting blocks and the start performances (SPs) of amputee sprinters (ASs) and non-amputee sprinters (NASs). SPs of 154 male and female NASs (100-m personal records [PRs], 9.58–14.00 s) and 7 male ASs (3 unilateral above knee, 3 unilateral below knee, 1 bilateral below knee; 100 m PRs, 11.70–12.70 s) with running specific prostheses (RSPs) were analysed during full-effort sprint starts using instrumented starting blocks that measured the applied forces in 3D. Using the NAS dataset and a combination of factor analysis and multiple regression techniques, we explored the relationship between force characteristics and SP (quantified by normalized average horizontal block power). Start kinetics were subsequently compared between ASs and NASs who were matched based on their absolute 100 m PR and their 100 m PR relative to the world record in their starting class. In NASs, 86% of the variance in SP was shared with five latent factors on which measured parameters related to force application to the rear and front blocks and the respective push-off directions in the sagittal plane of motion were loaded. Mediolateral force application had little influence on SP. The SP of ASs was significantly reduced compared to that of NASs matched on the basis of relative 100-m PR (−33.8%; d = 2.11, p < 0.001), while a non-significant performance reduction was observed when absolute 100-m PRs were used (−17.7%; d = 0.79, p = 0.09). These results are at least partially explained by the fact that force application to the rear block was clearly impaired in the affected legs of ASs.

Effects of increased toe flexor muscle strength to foot and ankle function in walking, running and jumping

Driven by experience and intuition, barefoot training is commonly used by athletes to increase foot muscle strength, to prevent injury and to enhance performance. With the aim to simulate barefoot ...

Aqua Cycling Does Not Affect Recovery of Performance, Damage Markers, and Sensation of Pain

Abstract Wahl, P, Sanno, M, Ellenberg, K, Frick, H, Böhm, E, Haiduck, B, Goldmann, J-P, Achtzehn, S, Brüggemann, G-P, Mester, J, and Bloch, W. Aqua cycling does not affect recovery of performance, damage markers, and sensation of pain. J Strength Cond Res 31(1): 162–170, 2017—To examine the effects of aqua cycling (AC) vs. passive recovery (P) on performance, markers of muscle damage, delayed onset of muscle soreness (DOMS), and the persons perceived physical state (PEPS) after 300 countermovement jumps (CMJs). Twenty male participants completed 300 CMJs. Afterward, they were randomly assigned to either the P group or the AC group, the latter performing 30 minutes of AC. Before, directly after the 300 CMJs, after the recovery session, and up to 72 hours post, performance of leg extensor muscles, damage markers, the PEPS, and DOMS were measured. Jumping height during 300 CMJs significantly decreased in both groups (AC: 13.4% and P: 14.6%). Maximal isometric strength (AC: 21% and P: 22%) and dynamic fatigue test (AC: 35% and P: 39%) of leg extensor muscles showed significant decreases in both groups. Myoglobin, creatine kinase, and lactate dehydrogenase significantly increased over time in both groups. Each of the 4 dimensions of the PEPS and DOMS showed significant changes over time. However, no significant differences between both groups were found for any of the parameters. Coaches and athletes should be aware that vertical jumping–induced fatigue decreases the ability to generate maximal isometric and submaximal dynamic force for more than 3 days after training. A single 30-minute session of AC was not able to attenuate the effects on muscular performance, markers of muscle damage, DOMS, or the PEPS compared with passive rest.

The gearing function of midsole longitudinal bending stiffness in running

Increasing the longitudinal bending stiffness (LBS) of running shoes (to an individual optimum level) has been shown to reduce energy absorption at the metatarsal phalangeal joint (MPJ) and has bee...