Danielle Formosa

London 2012 Paralympic swimming: passive drag and the classification system

Background The key difference between the Olympic and Paralympic Games is the use of classification systems within Paralympic sports to provide a fair competition for athletes with a range of physical disabilities. In 2009, the International Paralympic Committee mandated the development of new, evidence-based classification systems. This study aims to assess objectively the swimming classification system by determining the relationship between passive drag and level of swimming-specific impairment, as defined by the current swimming class. Methods Data were collected on participants at the London 2012 Paralympic Games. The passive drag force of 113 swimmers (classes 3–14) was measured using an electro-mechanical towing device and load cell. Swimmers were towed on the surface of a swimming pool at 1.5 m/s while holding their most streamlined position. Results Passive drag ranged from 24.9 to 82.8 N; the normalised drag (drag/mass) ranged from 0.45 to 1.86 N/kg. Significant negative associations were found between drag and the swimming class (τ=−0.41, p<0.01) and normalised drag and the swimming class (τ=−0.60, p<0.01). The mean difference in drag between adjacent classes was inconsistent, ranging from 0 N (6 vs 7) to 11.9 N (5 vs 6). Reciprocal Ponderal Index (a measure of slenderness) correlated moderately with normalised drag (rP=−0.40, p<0.01). Conclusions Although swimmers with the lowest swimming class experienced the highest passive drag and vice versa, the inconsistent difference in mean passive drag between adjacent classes indicates that the current classification system does not always differentiate clearly between swimming groups.

Front-crawl stroke-coordination and symmetry: A comparison between timing and net drag force protocols

Abstract This study compared stroke-coordination and symmetry using traditional timing methods and net drag force profiles. Twenty elite front-crawl swimmers Federation Internationale de Natation (FINA ranking 908 ± 59) were tested to identify the influence of both gender and breathing. A total of six randomised free-swimming trials were conducted: (i) three breathing, (ii) three non-breathing. Net drag forces were measured using an assisted towing device and the magnitude and location of minimum and maximum was determined to create a stroke symmetry index. Within the breathing condition, there were significant differences between the two symmetry index methods. Using the timing index, all 10 female participants, and seven males, illustrated symmetrical timing. For the net drag force profile, only three females and zero males exhibited a symmetrical minimum net drag force; and only four females and two males demonstrated a symmetrical maximum net drag force index. No differences existed within the non-breathing condition. There was a small (5.2%) difference in the location of maximum net drag force, when stratifying by gender. During the breathing condition, gender also influenced the percentage of overlap for the breathing stroke by 25.2%, and 14.6 % for the non-breathing stroke. A combination of the traditional timing based and net drag force based profile can guide future swimming technique intervention strategies.

Electromyographic responses during time get up and go test in water (wTUG).

The aim of this study was to use sEMG to measure the neuromuscular activity during the TUG task in water, and compare this with the responses for the same task on land. Ten healthy subjects [5 males and 5 females [mean ± SD]: age, 22.0 ± 3.1 yr; body mass, 63.9 ± 17.2 kg. A telemetry EMG system was used on the following muscles on the right side of the body: the quadriceps – rectus femoris [RF], long head of the biceps femoris [BF], tibialis anterior [TA], gastrocnemius medialis [GM], soleus [SOL], rectus abdominis [RA] and erector spinae [ES]. Each subject performed the TUG test three times with five minutes recover between trials in water and on dry land. The % MVC was significantly different (p < 0.05) for majority of the muscles tested during the TUG water compared to dry land. % MVC of RF [p = 0.003, t = 4.07]; BF [p = 0.000, t = 6.8]; TA [p = 0.005, t = 5.9]; and SOL [p = 0.048, t = 1.98]; RA [p = 0.007, t = 3.45]; and ES [p = 0.004, t = 3.78]. The muscle activation of the trunk and the lower limb [VM RF, BF, TA, GM and SOL] were lower in water compared to dry land, when performing a TUG test.

Quantifying stroke coordination during the breathing action in front-crawl swimming using an instantaneous net drag force profile

Abstract This study used both an instantaneous net drag force profile and a symmetry timing to evaluate the effect of the breathing action on stroke coordination. Twenty elite swimmers completed a total of six randomised front-crawl towing trials: (i) three breathing trials and (ii) three non-breathing trials. The net drag force was measured using an assisted towing device mounted upon a Kistler force platform, and this equipment towed the swimmer at a constant speed. The net drag force profile was used to create a stroke symmetry index for each swimming trial. Analysis using the symmetry indices identified that the majority of participants demonstrated an asymmetrical instantaneous net drag force stroke profile in both the breathing and non-breathing conditions, despite no significant differences in the time from finger-tip entry to finger-tip exit. Within the breathing condition, the faster swimmers compared to the slower swimmers demonstrated a lesser percentage of overlap between stroke phases on their breathing stroke side. During the non-breathing condition, the faster participants compared to the slower swimmers recorded a reduction in the percentage of overlap between stroke phases and less duration in the underwater stroke on their breathing stroke side. This study identified that the majority of participants demonstrated an asymmetrical net drag force profile within both conditions; however, asymmetry was less prevalent when examining with only the timing symmetry index.

Stroke-coordination and symmetry of elite backstroke swimmers using a comparison between net drag force and timing protocols

Abstract Stroke-coordination and symmetry influence the force fluctuations within any net drag force profile. The aim of this study was to analyse elite (FINA points 938) backstroke swimmers stroke-coordination using an instantaneous net drag force and timing protocols using a symmetry index tool. Ten male and nine female elite backstroke swimmers completed three maximum speed trials and five maximum speed net drag force swimming trials. Net drag force was measured using an assisted motorised dynamometer device. Each trial was filmed using three genlocked 50 Hz cameras, synchronised to the net drag force output from the force-platform. This methodology enabled the comparison of stroke-coordination timing symmetry index to net drag force symmetry index. The timing symmetry index and net drag force symmetry index yielded different results, the timing reflects the stroke-coordination, whilst the force index identified the effectiveness of the stroke. The only variable that was significantly different when comparing left and right stroke patterns was the location of minimum net drag forces. Conversely, gender influenced the location of maximum net drag force. Relationship analysis identified that location of maximum net drag force production was the only variable to correlate with speed within this cohort. Backstroke arm coordination was minimally influenced by gender.

Effectiveness of an Evidence-Based Multidisciplinary Falls Prevention Program in Reducing Falls in High-Risk Older People

To the Editor: The prevalence of falls in older people resulting in morbidity or death is continually increasing. Population studies have identified that approximately 20% of falls in adults aged 65 and older cause injury requiring medical treatment and that approximately 5% result in fracture injury. Intervention strategies have been shown to reduce the prevalence of falls significantly in older people in a community setting. Several factors have been shown to increase the risk of falling in older people, including impaired vision, peripheral sensation, muscle strength, reaction time, and balance. Pros and cons of single-intervention and multidisciplinary falls programs have been extensively discussed, highlighting that both types of programs are successful in falls prevention. Multifactorial fall interventions adopt a holistic approach involving functional, medical, and social aspects of assessing falls risk factors and devising an appropriate falls prevention plan and are therefore well suited to integration into existing and developing structures of coordinated care. The current study used a multidisciplinary falls prevention program to measure the effectiveness of reducing the number of falls and injuries in a high-risk population. The program was conducted by allied health practitioners with input from a geriatrician during the case conference where individualized management plans were generated. The initial consultation required participants to undergo a multidisciplinary falls risk assessment, including the Malnutrition Screening Tool (MST), a step test (worst leg), walking speed, the Modified Falls Efficacy Scale, the Physiological Profile Assessment (PPA), lying and standing blood pressures, and number of prescribed medications. Postassessment recommendations were provided to individuals based on the outcome measures and specialist observations. These recommendations for intervention included medical, environmental, exercise, community, and other. All participants underwent a bone health history for osteoporosis, and if they were not taking osteoporosis medication, a formal bone health assessment was recommended. After each participant received recommendations from the specialist panel, a repeat-measure 6-month follow-up visit was conducted. Initially, 86 participants entered the study and 51 participants (aged 77.5 8.8, 65% female) completed both the initial and 6-month assessments. The Queensland Health human research ethics committee approved procedures within this protocol before data collection. One-way analysis of variance testing was used to compare the initial and 6-month review data using SPSS (SPSS, Inc., Chicago, IL). Nonparametric chi-square testing was conducted to determine whether there was a reduction in reported medical attention between the initial assessment and the 6-month follow-up visit (Table 1). There was a significant (P = .04) reduction in the need for reported medical attention between the initial assessment and the 6-month follow-up consultation (Table 1). The fracture rates before and after the interventions were 19% to 3%. This multidisciplinary program to reduce falls, injuries, and the need for medical attention in older adults was successful, as a significant reduction in reported falls (66%), injuries (75%) and medical attention (77%) evidenced. The severity of the injuries was considerably less after the intervention, with a reduction in the number of reported fractures. These reductions could be a result of numerous contributing factors, including medication, environmental awareness, and improvement in physical fitness. Previous researchers have shown that reduction in psychotropic medication was positively associated with prevalence of falls in older adults. The current study demonstrated a 9% reduction of the number of prescribed medications. The findings provided additional evidence that a multidisciplinary falls clinic assessment and management program

The Influence of the Breathing Action on Net Drag Force Production in Front Crawl Swimming

20 elite swimmers completed a total of 6 randomized net drag force trials in 2 conditions (i) 3 breathing and (ii) 3 non-breathing. Net drag force was measured using an assisted motorized dynamometer device mounted upon a Kistler force-platform. The male participants demonstrated no statistical differences in stroke rates between breathing and non-breathing trials. Female participants, however, demonstrated a statistical difference stroke rate. The male participants demonstrated that the breathing action caused a greater (26%) net drag force compared to the females (16%). To further understand the influence of breathing on swimming technique, each stroke was analyzed and comparisons were made between the breathing and non-breathing conditions. The male participants demonstrated a similar minimum net drag force when comparing the breathing and non-breathing conditions. Analysis showed that minimum net drag force and maximum net drag force for the males changed when integrating the breathing action, while female participants demonstrated similar swimming technique, regardless of condition or stroke.