Breastfeeding media coverage and beliefs during the COVID-19 pandemic in Mexico: implications for breastfeeding equity.

BACKGROUND: Because breastfeeding offers short- and long- term health benefits to mothers and children, breastfeeding promotion and support is a public health priority. Evidence shows that SARS-CoV-2 is not likely to be transmitted via breastmilk. Moreover, antibodies against SARS-CoV-2 are thought to be contained in breastmilk of mothers with history of COVID-19 infection or vaccination. WHO recommends direct breastfeeding as the preferred infant feeding option during the COVID-19 pandemic, even among women with COVID-19; but conflicting practices have been adopted, which could widen existing inequities in breastfeeding. This study aims to describe how information about breastfeeding was communicated in Mexican media during the pandemic and assess Mexican adults' beliefs regarding breastfeeding among mothers infected with COVID-19. METHODS: We conducted a retrospective content analysis of media coverage on breastfeeding in Mexico between March 1 and September 24, 2020, excluding advertisements. For the content analysis, we performed both a sentiment analysis and an analysis based on strengths, weaknesses, opportunities, and threats (SWOT) for breastfeeding promotion. Additionally, we conducted a descriptive analysis of nationally representative data on adults' beliefs about breastfeeding from the July 2020 round of the ENCOVID-19 survey in Mexico and stratified the results by gender, age, and socioeconomic status. RESULTS: A total of 1014 publications on breastfeeding were identified on the internet and television and in newspapers and magazines. Most information was published during World Breastfeeding Week, celebrated in August. The sentiment analysis showed that 57.2% of all information was classified as positive. The SWOT analysis indicated that most information focused on current actions, messages, policies, or programs that enable breastfeeding (i.e., strengths) or those not currently in place but that may enable breastfeeding (i.e., opportunities) for breastfeeding promotion. However, ENCOVID-19 survey results showed that 67.3% of adults living in households with children under 3 years of age believe that mothers with COVID-19 should not breastfeed, and 19.8% do not know whether these mothers should breastfeed. These beliefs showed differences both by gender and by socioeconomic status. CONCLUSIONS: While the Mexican government endorsed the recommendation on breastfeeding during the COVID-19 pandemic, communication was sporadic, inconstant and unequal across types of media. There was a widespread notion that mothers with COVID-19 should not breastfeed and due to differences on beliefs by socioeconomic status, health inequities could be exacerbated by increasing the risk of poorer breastfeeding practices and preventing vulnerable groups from reaping the short and long-term benefits of breastfeeding.

Addressing noncommunicable diseases in primary care: the case of type 2 diabetes.

The rapid growth of noncommunicable diseases represents a formidable global health challenge. Here we use type 2 diabetes as a case study to illustrate the rise of noncommunicable diseases and call attention to the important role of primary care systems in addressing these diseases in low- and middle-income countries. Comprehensive screening for diabetes should be implemented through primary care systems to increase early detection of prediabetes and undiagnosed diabetes - a first step to diabetes prevention and management. In addition, primary care systems should strengthen and expand capacity to link patients to appropriate interventions based on their diabetes status and provide care coordination (e.g. leveraging task-shifting and technology), and integrate clinic and community resources for diabetes prevention and control. Additional strategies should include continuous quality improvement, health systems strengthening, workforce development, and affordable and sustainable financing. Together, these actions could elevate the role of primary care in addressing diabetes in low- and middle-income countries and help advance global progress towards reducing diabetes complications, and also preventing or delaying diabetes among those at risk.

The cutest little baby face: a hormonal link to sensitivity to cuteness in infant faces.

We used computer image manipulation to develop a test of perception of subtle gradations in cuteness between infant faces. We found that young women (19-26 years old) were more sensitive to differences in infant cuteness than were men (19-26 and 53-60 years old). Women aged 45 to 51 years performed at the level of the young women, whereas cuteness sensitivity in women aged 53 to 60 years was not different from that of men (19-26 and 53-60 years old). Because average age at menopause is 51 years in Britain, these findings suggest the possible involvement of reproductive hormones in cuteness sensitivity. Therefore, we compared cuteness discrimination in pre- and postmenopausal women matched for age and in women taking and not taking oral contraceptives (progestogen and estrogen). Premenopausal women and young women taking oral contraceptives (which raise hormone levels artificially) were more sensitive to variations of cuteness than their respective comparison groups. We suggest that cuteness sensitivity is modulated by female reproductive hormones.

Factors affecting performance in an ultraendurance triathlon.

In the recent past, researchers have found many key physiological variables that correlate highly with endurance performance. These include maximal oxygen uptake (VO2max), anaerobic threshold (AT), economy of motion and the fractional utilisation of oxygen uptake (VO2). However, beyond typical endurance events such as the marathon, termed 'ultraendurance' (i.e. >4 hours), performance becomes harder to predict. The ultraendurance triathlon (UET) is a 3-sport event consisting of a 3.8 km swim and a 180 km cycle, followed by a 42.2 km marathon run. It has been hypothesised that these triathletes ride at approximately their ventilatory threshold (Tvent) during the UET cycling phase. However, laboratory assessments of cycling time to exhaustion at a subject's AT peak at 255 minutes. This suggests that the AT is too great an intensity to be maintained during a UET, and that other factors cause detriments in prolonged performance. Potential defeating factors include the provision of fuels and fluids due to finite gastric emptying rates causing changes in substrate utilisation, as well as fluid and electrolyte imbalances. Thus, an optimum ultraendurance intensity that may be relative to the AT intensity is needed to establish ultraendurance intensity guidelines. This optimal UET intensity could be referred to as the ultraendurance threshold.

Physiological and cardiovascular changes associated with deep water running in the young. Possible implications for the elderly.

The increased number of people taking part in deep water running (DWR) is attributable to the weight-independent characteristic of this form of exercise. Deep water runners should, however, be aware of the respiratory and cardiovascular repercussions that result from exercising in water. It has been well documented that water immersion (WI) alone results in decrements in respiratory and cardiovascular parameters in young individuals immersed in water to the neck. These decrements become more pronounced with exercise, such that maximal oxygen consumption and heart rate (HR) are lower during DWR compared with running on land. Age also seems to influence these parameters; Derion et al. found little to no change in cardiac output, stroke volume and HR during WI in older individuals compared with the decrease experienced in younger individuals. In contrast, gender appears to have no effect on WI or DWR response. Although differences in acute metabolic responses have been observed in numerous studies, training studies examining the effectiveness of using a DWR training programme found that DWR produced equivocal training responses when compared with fit and highly trained individuals running on land. Less convincing evidence has been provided for untrained individuals seeking benefits from a DWR training programme, as some studies showed significant improvements while others did not. There is a current lack of knowledge regarding the use of this form of exercise by frail elderly individuals and/or those with osteoporosis.

The role of hyperbaric oxygen therapy in sports medicine.

During the past decade, we have seen a growing number of individuals participating in sport and recreational activities. All indications show an increase in sport participation at every age level. However, the number of sport and recreational injuries as a result of this increase has also risen. Unfortunately, a primary cost related to injury recovery is the time lost from participating in and resuming normal functional activity. This has compelled health care professionals to seek more efficient and effective therapeutic interventions in treating such injuries. Hyperbaric oxygen (HBO) therapy may serve to provide a means of therapy to facilitate a speedier resumption to pre-injury activity levels as well as improve the short and long term prognosis of the injury. Although a growing interest in sports medicine is becoming evident in the literature, the use of HBO as an intervention in this field has received a great deal of cynicism. To date, numerous professional athletic teams, including hockey (NHL), football (NFL), basketball (NBA) and soccer (MLS), utilise and rely on the use of HBO as adjuvant therapy for numerous sports-related injuries acquired from playing competitive sports. However, to date, very little has been published on the application benefits of hyperbaric therapy and sports injuries. The majority of clinical studies examining the efficacy of HBO in treating soft tissue injuries have been limited in their sample size and study design. Further research needs to be conducted suggesting and validating the significant effects of this treatment modality and further grounding its importance in sports medicine.

The effects of 3000-m swimming on subsequent 3-h cycling performance: implications for ultraendurance triathletes.

The purpose of this study was to examine the physiological effects of 3000-m swimming on subsequent 3-h cycling time trial performance in ultraendurance triathletes. Eight highly trained ultraendurance triathletes [mean (SEM) age 34 (2) years, body fat 12.5 (0.8)%, maximum oxygen consumption 63.2 (2.1) ml x kg(-1) x min(-1)] completed two randomly assigned trials 1 week apart. The swim/bike trial (SB) involved 3000 m of swimming [min:s 52:28 (1:48)] immediately followed by a 3-h cycling performance at a self-selected time-trial pace. The control trial (CON) consisted of an identical 3-h cycling time trial but without prior swimming. Subjects consumed an 8% carbohydrate (CHO)/electrolyte beverage during both trials at the rate of 60 g CHO x h(-1) and 1 l x h(-1). No significant differences were evident between CON and SB on the dependent measures (CON vs. SB): power output [W, 222 (14) W vs. 212 (13) W], heart rate [fc, 147 (5) beats x min(-1) vs. 143 (4) beats min(-1); %fcmax 80.0 (1.6)% vs. 78.4 (1.5)%], oxygen uptake [3.10 (0.12) l x min(-1) vs. 2.97 (0.15) l x min(-1)], minute ventilation [82.5 (4.4) l x min(-1) vs. 77.3 (3.7) l x min(-1)], rating of perceived exertion [14.6 (0.4) vs. 14.0 (0.1)], blood lactate [6.1 (0.5) mmol x l(-1) vs. 4.8 (0.5) mmol x l(-1)], and blood glucose [5.0 (0.2) mmol x l(-1) vs. 5.3 (0.1) mmol x l(-1); all non-significant at the P>0.05 level]. However, the CON respiratory exchange ratio was significantly greater than for SB [0.91 (0.01) vs. 0.89 (0.01); P<0.05], suggesting that the SB trial required a greater reliance on lipid as a fuel substrate. Hence, the main finding in the present study was that 3000 m of swimming had no significant performance effect (in terms of W) on subsequent 3-h cycling performance in ultraendurance triathletes.

A review of the concept of the heart rate deflection point.

The heart rate deflection point (HRDP) is a downward or upward change from the linear HR-work relationship evinced during progressive incremental exercise testing. The HRDP is reported to be coincident with the anaerobic threshold. In 1982, Conconi and colleagues suggested that this phenomenon could be used as a noninvasive method to assess the anaerobic threshold. These researchers developed a field test to assess the HRDP, which has become popularised as the 'Conconi test'. Concepts used to define and assess the anaerobic threshold as well as methodological procedures used to determine the HRDP are diverse in the literature and have contributed to controversy surrounding the HRDP concept. Although the HRDP may be assessed in either field or laboratory settings, the degree of HR deflection is highly dependent upon the type of protocol used. The validity of HRDP to assess the anaerobic threshold is uncertain, although a high degree of relationship exists between HRDP and the second lactate turnpoint. The HRDP appears to be reliable when a positive identification is made; however, not all studies report 100% reproducibility. Although the physiological mechanisms explaining the HRDP are unresolved, a relationship exists between the degree and direction of HRDP and left ventricular function. The HRDP has potential to be used for training regulation purposes. Clinically, it may be incorporated to set exercise intensity parameters for cardiac rehabilitation.

Effects of one year of resistance training on the relation between muscular strength and bone density in elderly women.

OBJECTIVES: There is a paucity of long term studies on exercise training in elderly women. The purpose of this study was to investigate the effects of one year of progressive resistance exercise (PRE) on dynamic muscular strength and the relations to bone mineral density (BMD) in elderly women. METHODS: Forty four healthy sedentary women (mean age 68.8 years) volunteered for this study and were randomly assigned to either an exercise group or a control group. The exercise group were involved in three one hour sessions a week for 52 weeks of supervised PRE to strengthen the large muscle groups of the body, while the control group were instructed to continue their normal lifestyle. The exercise circuit included three sets of eight repetitions at 75% of one repetition maximum focused on the large muscle groups. BMD was measured by dual energy x ray absoptiometry (Lunar DPX) at the lumbar spine and at three sites in the proximal femur. Other selected parameters of physical fitness were also measured. RESULTS: Statistical analyses (analysis of covariance) showed significant strength gains (p < 0.01) in bilateral bench press (> 29%), bilateral leg press (> 19%), and unilateral biceps curl (> 20%). No significant difference between groups was evident in body weight, grip strength, flexibility, waist to hip ratio, or the sum of eight skinfolds. Significant relations (p < 0.05) were recorded between dynamic leg strength and the BMD of the femoral neck, Ward's triangle, and the lumbar spine. CONCLUSIONS: Significant strength changes, after one year of PRE, were evident in elderly women, and the muscle increases may parallel changes in BMD; however, correlation coefficients were moderate.

Metabolic responses to prolonged work during treadmill and water immersion running.

The primary aim of this study was to compare the physiological responses to prolonged treadmill (TM) and water immersion to the neck (WI) running at threshold intensity. Ten endurance runners performed TM and WI running VO2max tests. Subjects completed submaximal performance tests at ventilatory threshold (Tvent) intensities under TM and WI conditions and responses at 15 and 42 minutes examined. VO2 was lower in WI (p<0.05) at maximal effort and Tvent. The Tvent VO2 intensities interpolated from the TM and WI VO2max tests were performed in both TM (i.e., TM@TM(tvent),TM@WI(tvent), corresponding to 77.6 and 71.3% respectively of TM VO2max) and WI conditions (i.e., WI@TM(tvent), WI@WI(tvent), corresponding to 85.5% and 78.2% respectively of WI VO2max). Each of the dependent variables was analyzed using a 3-way repeated measures ANOVA (2 conditions X 2 exercise intensities X 7 time points during exercise). VO2max values were significantly lower in the WI (52.4(5.1) ml.kg(-1) min(-1)) versus TM (59.7(6.5) ml.kg(-1) min(-1)) condition. VO2 during submaximal tests were similar during the TM and WI conditions. HR and [BLa] responses to exercise at and above WI(tvent) were similar during short-term exercise, but values tended to be lower during prolonged exercise in the WI condition. There were no statistical differences in VE responses in the 2 conditions, however as with HR and [BLa] an upward trend was noted with TM exercise over the 42 minute duration of the tests. RPE at WI(tvent) was similar for TM and WI exercise sessions, however, RPE at TM(tvent) was higher during WI compared to TM running. Cardiovascular drift was observed during prolonged TM but not WI running. Results suggest differences in metabolic responses to prolonged submaximal exercise in WI, however it can be used effectively for cross training.

Effects of creatine supplementation on exercise performance.

While creatine has been known to man since 1835, when a French scientist reported finding this constitutent of meat, its presence in athletics as a performance enhancer is relatively new. Amid claims of increased power and strength, decreased performance time and increased muscle mass, creatine is being hailed as a true ergogenic aid. Creatinine is synthesised from the amino acids glycine, arginine and methionine in the kidneys, liver and pancreas, and is predominantly found in skeletal muscle, where it exists in 2 forms. Approximately 40% is in the free creatine form (Crfree), while the remaining 60% is in the phosphorylated form, creatine phosphate (CP). The daily turnover rate of approximately 2 g per day is equally met via exogenous intake and endogenous synthesis. Although creatine concentration (Cr) is greater in fast twitch muscle fibres, slow twitch fibres have a greater resynthesis capability due to their increased aerobic capacity. There appears to be no significant difference between males and females in Cr, and training does not appear to effect Cr. The 4 roles in which creatine is involved during performance are temporal energy buffering, spatial energy buffering, proton buffering and glycolysis regulation. Creatine supplementation of 20 g per day for at least 3 days has resulted in significant increases in total Cr for some individuals but not others, suggesting that there are 'responders' and 'nonresponders'. These increases in total concentration among responders is greatest in individuals who have the lowest initial total Cr, such as vegetarians. Increased concentrations of both Crfree and CP are believed to aid performance by providing more short term energy, as well as increase the rate of resynthesis during rest intervals. Creatine supplementation does not appear to aid endurance and incremental type exercises, and may even be detrimental. Studies investigating the effects of creatine supplementation on short term, high intensity exercises have reported equivocal results, with approximately equal numbers reporting significant and nonsignificant results. The only side effect associated with creatine supplementation appears to be a small increase in body mass, which is due to either water retention or increased protein synthesis.

Oxygen uptake kinetics during exercise.

The characteristics of oxygen uptake (VO2) kinetics differ with exercise intensity. When exercise is performed at a given work rate which is below lactate threshold (LT), VO2 increases exponentially to a steady-state level. Neither the slope of the increase in VO2 with respect to work rate nor the time constant of VO2 responses has been found to be a function of work rate within this domain, indicating a linear dynamic relationship between the VO2 and the work rate. However, some factors, such as physical training, age and pathological conditions can alter the VO2 kinetic responses at the onset of exercise. Regarding the control mechanism for exercise VO2 kinetics, 2 opposing hypotheses have been proposed. One of them suggests that the rate of the increase in VO2 at the onset of exercise is limited by the capacity of oxygen delivery to active muscle. The other suggests that the ability of the oxygen utilisation in exercising muscle acts as the rate-limiting step. This issue is still being debated. When exercise is performed at a work rate above LT, the VO2 kinetics become more complex. An additional component is developed after a few minutes of exercise. The slow component either delays the attainment of the steady-state VO2 or drives the VO2 to the maximum level, depending on exercise intensity. The magnitude of this slow component also depends on the duration of the exercise. The possible causes for the slow component of VO2 during heavy exercise include: (i) increases in blood lactate levels; (ii) increases in plasma epinephrine (adrenaline) levels; (iii) increased ventilatory work; (iv) elevation of body temperature; and (v) recruitment of type IIb fibres. Since 86% of the VO2 slow component is attributed to the exercising limbs, the major contributor is likely within the exercising muscle itself. During high intensity exercise an increase in the recruitment of low-efficiency type IIb fibres (the fibres involved in the slow component) can cause an increase in the oxygen cost of exercise. A change in the pattern of motor unit recruitment, and thus less activation of type IIb fibres, may also account for a large part of the reduction in the slow component of VO2 observed after physical training.

Aerobic and anaerobic energy during a 2-km race simulation in female rowers.

The maximal aerobic power (VO2max) and maximal anaerobic capacity (AODmax) of 16 female rowers were compared to their peak aerobic power (VO2peak) and peak anaerobic capacity (AODpeak, respectively) during a simulated 2-km race on a rowing ergometer. Each subject completed three tests, which included a 2-min maximal effort bout to determine the AODmax, a series of four, 4-min submaximal stages with subsequent progression to VO2max and a simulated 2-km race. Aerobic power was determined using an open-circuit system, and the accumulated oxygen deficit method was used to calculate anaerobic capacities from recorded mechanical power on a rowing ergometer. The average VO2peak (3.58 l min(-1)), which usually occurred during the last minute of the race simulation, was not significantly different (P > 0.05) from the VO2max (3.55 l min(-1)). In addition, the rowers' AODmax (3.40 l) was not significantly different (P > 0.05) from their AODpeak (3.50 1). The average time taken for the rowers to complete the 2-km race simulation was 7.5 min, and the anaerobic system (AODpeak) accounted for 12% of the rowers' total energy production during the race.

Factors associated with exercise adherence among older adults. An individual perspective.

This paper reviews the literature concerning factors at the individual level associated with regular exercise among older adults. Twenty-seven cross-sectional and 14 prospective/longitudinal studies met the inclusion criteria of a mean participant age of 65 years or older. The findings are summarised by demographics, exercise experience, exercise knowledge, physiological factors, psychological factors, activity preferences and perceived social influences. In general, education and exercise history correlate positively with regular exercise, while perceived physical frailty and poor health may provide the greatest barrier to exercise adoption and adherence in the elderly. Social-cognitive theories identify several constructs that correlate with the regular exercise behaviour of older adults, such as exercise attitude, perceived behavioural control/self-efficacy, perceived social support and perceived benefits/barriers to continued activity. As well, stage modelling may provide additional information about the readiness for regular exercise behaviour among older adults. However, relatively few studies among older adults exist compared with middle-aged and younger adults. Further, the majority of current research consists of cross-sectional designs or short prospective exercise trials among motivated volunteers that may lack external validity. Future research utilising longitudinal and prospective designs with representative samples of older adults will provide a better understanding of significant causal associations between individual factors and regular exercise behaviour.

Lipid metabolism during exercise.

Fat is an extremely important substrate for muscle contraction, both at rest and during exercise. Triglycerides (TGs), stored in adipose tissue and within muscle fibres, are considered to be the main source of the free fatty acids (FFAs) oxidised during exercise. It is still unclear, however, how the use of these substrates is regulated during exercise. The regulation seems to be multifactorial and includes: (i) dietary and nutritional status; (ii) hormonal milieu; (iii) exercise mode, intensity and duration; and (iv) training status. On the other hand, the mechanism for FFA transport from its storage as triglycerides in adipose tissue and muscle to its place of utilisation in heart, skeletal muscle, kidney and liver is more clearly understood. It has been determined that the plasma FFA turnover rate is sufficiently rapid to account for most of the fat metabolised during low intensity exercise (25 to 40% VO2max). However, an exercise intensity of 65% VO2max results in a slight decrease in the amount of plasma FFA uptake by muscle tissue. Other studies have found that during prolonged exercise, muscle TGs become the predominant source of energy obtained from fat. Furthermore, it is widely documented that endurance activities increase the energy utilisation from fat while sparing carbohydrate sources. For example, during exercise on a cycle ergometer, nonplasma FFAs and plasma FFAs contribute 40%, and carbohydrates 60%, of the total calculated amount of energy expenditure before exercise and vice versa after exercise (60% nonplasma and plasma FFAs and 40% carbohydrates). Although it was many years before it was fully demonstrated, fat is now known to be transported in the blood as FFA bound to the protein carrier albumin. The mobilisation of FFA is primarily a function of sympathetic nervous activity directed towards the adipocytes, or the 'fat pad'. This nervous activity can be direct or may be an effect of circulating catecholamines such as adrenaline (epinephrine). This article summarises the role of fat metabolism during exercise.

Glycaemic index and optimal performance.

It is widely documented that athletes should consume carbohydrates prior to, during and after exercise. Ingestion of carbohydrates at these times will optimise performance and recovery. In spite of this knowledge, there is a paucity of information available to athletes concerning the types of carbohydrate foods to select. Therefore, it is suggested that the glycaemic index may be an important resource when selecting an ideal carbohydrate. The glycaemic index categories foods containing carbohydrates according to the blood glucose response that they elicit. Carbohydrate foods evoking the greatest responses are considered to be high glycaemic index foods, while those producing a relatively smaller response are categorised as low glycaemic index foods. Athletes wishing to consume carbohydrates 30 to 60 minutes before exercise should be encouraged to ingest low glycaemic index foods. Consuming these types of foods will decrease the likelihood of creating hyperglycaemia and hyperinsulinaemia at the onset of exercise, while providing exogenous carbohydrate throughout exercise. It is recommended that high glycaemic index foods be consumed during exercise. These foods will ensure rapid digestion and absorption, which will lead to elevated blood glucose levels during exercise. Post-exercise meals should consist of high glycaemic index carbohydrates. Low glycaemic foods do not induce adequate muscle glycogen resynthesis compared with high glycaemic index foods.

Exercise for the older woman: choosing the right prescription.

Many elderly women in industrially developed countries are at, or near to, functionally important strength related thresholds and so have either lost, or are in danger of losing, the ability to perform some important everyday tasks. The increased rate of healthcare expenditure due to loss of physical function is a major economic issue. Even though women make up most of the senior population, little current research on the impact of physical activity on strength and function in elderly people has included women. Elderly women typically have more barriers to participation in physical activity than do other groups and because of decreased participation, may possibly experience higher disability rates. Physical activity in old age may delay the progression of osteoporosis and is of paramount importance for maintaining the functional abilities needed to carry out daily tasks. Current research on exercise and the elderly population suggests that strength training may be the exercise mode of choice for maintenance of strength, physical function, bone integrity, and psychosocial health. This review summarises recent research on the impact of strength training on the fitness and health of elderly women and highlights considerations and potential barriers to physical activity that must be taken into account when planning exercise programmes for them.

Maintenance of aerobic capacity during recovery from right foot Jones fracture: a case report.

PURPOSE: We sought to evaluate the effectiveness of continued training with deep water running (DWR) on the healing process from a lower leg fracture in maintaining aerobic fitness. CASE SUMMARY: An elite male middle distance runner presented with a Jones fracture of the right foot. The patient opted for nonsurgical treatment. Non-weight-bearing immobilization in a cast proceeded for 14 weeks. The patient continued training by simulating land running and team land workouts with DWR. DWR was the principal mode of exercise through week 24. Physiological and race performance assessments noted a progressive and complete return to preinjury fitness and performance levels. DISCUSSION: DWR can be used by competitive runners during a rehabilitative period to maintain fitness and does not impede the healing process. In developing a DWR regimen, it should be noted that the exercise heart rate when working above the ventilatory threshold will be approximately 12 bpm lower in water. RELEVANCE: DWR may be feasible for maintenance of competitive edge during lower trunk injury rehabilitation.

Comparison of a mathematical model to predict 10-km performance from the Conconi test and ventilatory threshold measurements.

The purpose of this study was to validate a mathematical model (MM) that evaluates the Conconi test and predicts 10-km race time. In addition, the relationship between ventilatory threshold (Tvent) determined from a laboratory test and heart rate deflection (HRd) from the Conconi test were examined. Seventeen trained runners performed the Conconi test, and performance times were predicted using a MM based on a logistics function. A correlational analysis indicated a highly significant relationship (r = .98, p < .01) between MM predicted time and actual time. Significant relationships were found between velocity at Tvent and HRd (r = .95, p < .01), and predicted times from each method (r = .96, p < .01). Heart rates from Tvent and HRd were also related (r = .79, p < .01). These results suggest that a MM of the Conconi test is a valid method of predicting 10-km performance and is closely related to traditional laboratory measures.