EFFECTS OF IMPOSED CYCLE FREQUENCY TRAINING ON THE HEAVE AND PITCH PHASE RELATIONSHIPS IN UNDULATORY UNDERWATER SWIMMING

This study compared the effects of training at a self-selected preferred cycle frequency (PF) with an identical imposed cycle frequency (IF) on the heave and pitch phase relationship in undulatory underwater swimming (UUS), to examine the effects of frequency imposition on coordination. Kinematic data were recorded from 16 skilled swimmers performing maximal UUS prior to and during 4-weeks UUS training at either their PF or an IF set at their preferred frequency, with weekly testing sessions and final retest session 2-weeks post training. No differences in maximal swimming velocity were found. No differences were found in heave and pitch phase relationship between training groups. Further research is required to establish the efficacy of heave and pitch coupling as an effective measure of UUS behaviour in skilled swimmers

Relationships between glide efficiency and swimmers' size and shape characterisitics

Glide efficiency, the ability of a body to minimize deceleration over the glide, can change with variations in the body’s size and shape. The purpose of this study was to investigate the relationships between glide efficiency and the size and shape characteristics of swimmers. Eight male and eight female swimmers performed a series of horizontal glides at a depth of 70 cm below the surface. Glide efficiency parameters were calculated for velocities ranging from 1.4 to 1.6 m/s for female swimmers (and at the Reynolds number of 3.5 million) and from 1.6 to 1.8 m/s for male swimmers (and at the Reynolds number of 4.5 million). Several morphological indices were calculated to account for the shape characteristics, with the use of a photogrammetric method. Relationships between the variables of interest were explored with correlations, while repeated-measures ANOVA was used to assess within-group differences between different velocities for each gender group. Glide efficiency of swimmers increased when velocity decreased. Some morphological indices and postural angles showed a significant correlation with glide efficiency. The glide coefficient was significantly correlated to the chest to waist taper index for both gender groups. For the male group, the glide coefficient correlated significantly to the fineness ratio of upper body, the chest to hip cross-section. For the female group the glide coefficient had a significant correlation with the waist to hip taper index. The findings suggested that gliding efficiency was more dependent on shape characteristics and appropriate postural angles rather than being dependent on size characteristics

Relationships between glide efficiency and swimmers' size and shape characterisitics

Glide efficiency, the ability of a body to minimize deceleration over the glide, can change with variations in the body’s size and shape. The purpose of this study was to investigate the relationships between glide efficiency and the size and shape characteristics of swimmers. Eight male and eight female swimmers performed a series of horizontal glides at a depth of 70 cm below the surface. Glide efficiency parameters were calculated for velocities ranging from 1.4 to 1.6 m/s for female swimmers (and at the Reynolds number of 3.5 million) and from 1.6 to 1.8 m/s for male swimmers (and at the Reynolds number of 4.5 million). Several morphological indices were calculated to account for the shape characteristics, with the use of a photogrammetric method. Relationships between the variables of interest were explored with correlations, while repeated-measures ANOVA was used to assess within-group differences between different velocities for each gender group. Glide efficiency of swimmers increased when velocity decreased. Some morphological indices and postural angles showed a significant correlation with glide efficiency. The glide coefficient was significantly correlated to the chest to waist taper index for both gender groups. For the male group, the glide coefficient correlated significantly to the fineness ratio of upper body, the chest to hip cross-section. For the female group the glide coefficient had a significant correlation with the waist to hip taper index. The findings suggested that gliding efficiency was more dependent on shape characteristics and appropriate postural angles rather than being dependent on size characteristics.</jats:p

TADPOLE, TROUT OR TUNA: THE EQUIVALENCE OF ANIMAL AND HUMAN AQUATIC UNDULATORY LOCOMOTION.

The purpose of this study was to examine the kinematics of human undulatory underwater swimming and compare the principle components of the propulsive waveform to those generated in the various modes of animal undulatory locomotion. Results indicated a similarity to a sub-carangiform mode of locomotion, with minimal undulation in the anterior aspects of the body and less than one wavelength present on the swimming body. A sub-cariangiform mode of locomotion suggests that swimmers’ arms are acting as inertial dampers, reducing dorso-ventral movements (pitch) in the anterior aspects of the body, and thereby minimising form drag and allowing a more efficient transfer of the propulsive wave along the caudal aspects of the swimmer

Tadpole, trout or tuna: the equivalence of animal and human aquatic undulatory locomotion.

The purpose of this study was to examine the kinematics of human undulatory underwater swimming and compare the principle components of the propulsive waveform to those generated in the various modes of animal undulatory locomotion. Results indicated a similarity to a sub-carangiform mode of locomotion, with minimal undulation in the anterior aspects of the body and less than one wavelength present on the swimming body. A sub-cariangiform mode of locomotion suggests that swimmers’ arms are acting as inertial dampers, reducing dorso-ventral movements (pitch) in the anterior aspects of the body, and thereby minimising form drag and allowing a more efficient transfer of the propulsive wave along the caudal aspects of the swimmer

Rolling actions of shoulders and hips in freestyle swimming.

The purpose of this study was to determine accurately the magnitude of shoulder roll (SR) and hip roll (HR) in freestyle swimming, to assess the significance of the differences between these parameters and to examine whether they are associated with swimming velocity (V). Six male swimmers of national and international level performed a maximum freestyle swim. One non-breathing stroke cycle was selected for analysis. It was shown that swimmers rolled their shoulders significantly more than their hips. Faster swimming velocities were associated with smaller magnitudes of SR, but no significant correlations were found for V and HR. These results indicated that SR and HR need to be examined separately in freestyle swimming, as the measurement of body roll for the whole trunk does not represent with validity the rolling characteristics of the trunk

ROLLING ACTIONS OF SHOULDERS AND HIPS IN FREESTYLE SWIMMING

The purpose of this study was to determine accurately the magnitude of shoulder roll (SR) and hip roll (HR) in freestyle swimming, to assess the significance of the differences between these parameters and to examine whether they are associated with swimming velocity (V). Six male swimmers of national and international level performed a maximum freestyle swim. One non-breathing stroke cycle was selected for analysis. It was shown that swimmers rolled their shoulders significantly more than their hips. Faster swimming velocities were associated with smaller magnitudes of SR, but no significant correlations were found for V and HR. These results indicated that SR and HR need to be examined separately in freestyle swimming, as the measurement of body roll for the whole trunk does not represent with validity the rolling characteristics of the trunk

LOAD CARRIAGE ALTERS TIBIOFEMORAL KINEMATICS DURING SLOW JOGGING IN ADULT MEN AND WOMEN

The purpose of this investigation was to determine the effects of load carriage on tibiofemoral kinematics during running. Nineteen healthy, recreationally active adults completed dynamic biplane radiography trials of the dominant limb knee with no load (BW), and an additional 55% of body weight (+55%BW) while running 10% above gait transition velocity. A volumetric model-based tracking technique was utilized to derive medial translation excursion, proximal (inferior-superior) translation excursion, anterior translation excursion, flexion, internal rotation and abduction. At heel strike, running with +55%BW exhibited a more flexed knee compared to BW. However, BW exhibited more proximal translation excursion compared to +55%BW. By contrast, +55%BW had greater anterior translation excursion compared to BW. There were no significant differences between BW and +55%BW for medial translation excursion, internal rotation angle/excursion or abduction angle/excursion The greater knee flexion angle at heel strike for +55%BW may serve as a mechanism to better attenuate the greater impact force via eccentric muscle action. However, reduced proximal translation excursion during +55%BW could suggest greater loading of the soft tissues

Comparison of Heart Rate Responses Between Coronary Heart Disease and Age-Matched Normal Subjects in Water-and Land-Based Exercise: A Pilot Study

Background and purpose. Exercise therapy is an integral component of cardiac rehabilitation (CR). Currently, land-based exercise classes are prescribed in Phase IV CR. However, with its unique properties, water-based exercise potentially offers an alternative, or additional mode of exercise, that could be utilized by rehabilitating individuals. The purpose of this pilot study was to measure and compare the heart rate (HR) response and perception of exercise intensity between similar land-and water-based classes

Impact of Increased Load Carriage Magnitude on the Dynamic Postural Stability of Men and Women

The impact of load carriage on dynamic postural stability affects the survivability of the Warfighter by influencing performance capabilities and injury incidence. Further, sex may interact with the relationship between load carriage and dynamic postural stability to further compromise survivability. PURPOSE: To investigate the effect of load carriage magnitude on dynamic postural stability of men and women and its relationship to jumping ability. METHODS: 32 subjects (16 men, 16 women) were investigated for maximum jump height and dynamic postural stability. Dynamic postural stability was assessed by subjects jumping a horizontal distance of 40% their height over a 30cm hurdle, landing on one leg on a force plate (sample rate = 1200 Hz). 3 trials were completed for 3 load conditions: +0, +20 and +30% body weight (BW). Dynamic postural stability was determined from ground reaction force data during landings, by calculation of the dynamic postural stability index (DPSI). Maximum jump height was assessed by subjects performing 3 countermovement jumps (sample rate = 1000 Hz). Two-way repeated measures ANOVA were used to compare mean DPSI scores between sexes and conditions (α = 0.05). Pearson’s Correlation Coefficients were used to determine the relationship between jump height and change in DPSI scores between conditions (α = 0.05). RESULTS: Load condition significantly affected DPSI (F = 100.304, p = 0.001). DPSI scores increased between the 0% (0.359 ± 0.041), 20% (0.396 ± 0.034) and 30% (0.420 ± 0.028) BW load conditions. No significant effect of sex on DPSI was found (F = 0.131). No significant sex by load interaction on DPSI was found (F = 0.393). No significant correlations were found between jump height and change in DPSI scores between conditions. CONCLUSION: Increased load was found to negatively affect dynamic postural stability, most likely as a result of modifying the demands of the task. Therefore, the dynamic postural stability of men and women changes comparably in response to increased load carriage magnitude. Future research should focus on the effects of load on dynamic postural stability under higher loads and during more military-specific tasks