David Robert Pendergast

• University at Buffalo, State University of New York

Introduction: Head-out water immersion (HOWI) results in diuresis, which could potentially limit performance after egress to land. We examined the effect of rehydration on endurance, cardiovascular stability, and overnight recovery following a four-hour thermoneutral HOWI on 12 subjects. Methods: Twelve males completed a crossover design consist...

Objective Firefighters are required to use self-contained breathing apparatus (SCBA), which impairs ventilatory mechanics. We hypothesized that firefighters have elevated arterial CO2 when using SCBA. Methods Firefighters and controls performed a maximal exercise test on a cycle ergometer and two graded exercise tests (GXT) at 25%, 50%, and 70% of...

Using theoretical principles, the components of drag (friction DF, pressure DPR and wave DW) of a single-seat kayak were analysed. The purpose was to examine the effect of changes in wetted surface area due to changes in kayaker’s weight and the relative contribution of DF, DPR and DW to the total passive drag as function of velocity. The total pas...

The aim of this study was to compare the non-linear properties of the four competitive swim strokes. Sixty-eight swimmers performed a set of maximal 4 × 25 m using the four competitive swim strokes. The hip's speed-data as a function of time was collected with a speedo-meter. The speed fluctuation (dv), approximate entropy (ApEn) and the fractal di...

Our purpose was to examine the swimming biophysical responses at velocities (v) of 97.5, 100 and 102.5% of the maximal lactate steady state (MLSS). Ten elite female swimmers performed three-to-five 30-min constant tests at imposed paces to determine 97.5, 100 and 102.5%MLSS v. Gas exchange, blood lactate concentration ([La-]), stroke rate (SR) and...

BACKGROUND: Climbing and trekking at altitude are common recreational and military activities. Physiological effects of altitude are hypoxia and hyperventilation. The hyperventilatory response to altitude may cause respiratory muscle fatigue and reduce sustained submaximal exercise. Voluntary isocapnic hyperpnea respiratory muscle training (VIHT) i...

Background: Hiking and trekking often occur at altitudes up to 12,000 ft altitude. The hypoxia-induced hyperventilation at altitude paradoxically reduces arterial CO2 (Paco2). A reduction in Paco2 results in vasoconstriction of the blood vessels of the brain and thus in local hypoxia. The local hypoxia likely affects cognitive function, which may...

Drag is one of the major factors that influences kayaking performance. To focus on the drag of the kayak's hull shape and the paddlers' weight per se, the passive drag (Dp) was measured on a flat-water sprint course for one paddler with added weights. Dp was measured by an electromechanical towing device using a load cell, at incremental and consta...

Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head-out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and ele...

Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head‐out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and ele...

Tissue nitrogen (N2) exchange is primarily dependent on circulation, which may be modified by body thermal status. Thermal effects on uptake and washout of N2 have not been systematically investigated earlier. In the present study of eight subjects, N2 was washed out in thermally neutral ambient conditions (TN; skin temperature (Ts) = 33.69 ± 0.84...

Some patients with postconcussion syndrome (PCS) have reduced exercise capacity that may reflect altered central cardiorespiratory control. The purpose of this study was to evaluate control of cerebral blood flow (CBF) during exercise in females with PCS. University Concussion Clinic. Nine female Division 1 collegiate team athletes with PCS (23 ± 6...

Introduction: Exposure to high altitude decreases arterial oxygen saturation (Sa(O2)). Previous studies have shown decreased voltage of the T wave of the electrocardiogram (ECG) at altitudes up to 7000 m (22,966 ft) secondary to hypoxia. This pilot study explored changes in the ECG at the maximum altitude pilots can fly without supplemental oxygen...

Resistance respiratory muscle training (RRMT) increases respiratory muscle strength and can increase swimming endurance time by as much as 85%. The purpose of this study was to examine potential mechanisms by which RRMT improves exercise endurance. Eight healthy adult male scuba divers underwent experiments in a hyperbaric chamber at sea level (1 a...

Swimming has become one important area of sport science research since the 1970s, with the bioenergetical factors assuming a fundamental performance-influencing role. The purpose of this study is to conduct a critical evaluation of the literature concerning the oxygen uptake (VO2) assessment in swimming, by describing the equipment and methods used...

During denitrogenation for rescue, crew members of an internally pressurized disabled submarine (DISSUB) must sit upright, which may hamper venous return, cardiac output and peripheral circulation. Since negative pressure breathing (NPB) might counteract this problem, denitrogenation was measured in sitting subjects performing NPB. Seven male subje...

Submersion and increased pressure (depth) characterize the diving environment and may independently increase demand on the respiratory system. To quantify changes in respiratory mechanics, this study employed a unique protocol and techniques to measure, in a hyperbaric chamber, inspiratory and expiratory alveolar pressures (P(AI) and P(AE), interru...

This study aimed to determine the relative contribution of selected biomechanical, energetic, coordinative, and muscular factors for the 200 m front crawl and each of its four laps. Ten swimmers performed a 200 m front crawl swim, as well as 50, 100, and 150 m at the 200 m pace. Biomechanical, energetic, coordinative, and muscular factors were asse...

Introduction: Reduced VO2peak, muscle mass, increased fat mass and immunosenescence have been associated with aging. This study examined the effects of exercise on selected cytokines in younger and older individuals, and after 12 weeks of aerobic exercise training in older individuals. Methods: Serum levels of interleukin-6 (IL-6), interleukin-1 be...

Purpose: To compare functional magnetic resonance imaging (fMRI) activation patterns during a cognitive task, exercise capacity, and symptoms in postconcussion syndrome (PCS) patients who received exercise treatment (n = 4) with a PCS placebo stretching group (n = 4) and a healthy control group (n = 4). Methods: Subjects completed a math process...

Respiratory muscle training against resistance (RRMT) increases respiratory muscle strength and endurance as well as underwater swimming endurance. We hypothesized that the latter is a result of RRMT reducing the high energy cost of breathing at depth. Eight subjects breathed air in a hyperbaric chamber at 55 fsw, both before and after RRMT. They r...

The reduced cardiac output (CO) secondary to increased acceleration forces (+Gz) has applicability to daily life and pathophysiology. Increased +Gz and reduced CO affect the lung, resulting in reduced oxygen transport. A variety of studies have examined tolerance to high +Gz. The present study examines the effect of +1 to +3 Gz on steady-state card...

To compare two different types of respiratory muscle training on exercise performance, a protocol was devised consisting of a combination of a 4-week, 12-session resistive respiratory muscle training (RRMT) followed by a 4-week, 12-session voluntary isocapnic hyperpnea training (VIHT) and conducted in experienced runners (4 men, 4 women). Measureme...

Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG CoA] reductase inhibitors) reduce blood lipoproteins and reduce the risk of cardiovascular events. However, they may reduce fat metabolism. This study tested the hypothesis that total body fat oxidation is reduced by statins in older subjects and the reduction is not due to substrate availability....

Because it has earlier been shown that exercise 24 or two hours pre-dive may suppress the appearance of venous gas bubbles (VGB) in connection with the dive, we studied whether exercise before or during N2 elimination would influence the rate of the latter. Nitrogen elimination was recorded in eight volunteers breathing a normoxic O2+argon mixture...

Background: Previous studies have suggested reduced fat metabolism in older subjects. However, corrections for their reduced maximal oxygen consumption and the effects of training and substrate availability have not been fully examined. Objectives: Fat metabolism (FM) in older subjects (n = 14, 75 ± 7 yrs), and the effects of exercise training were...

The energy cost to swim a unit distance (C(sw)) is given by the ratio E/v where E is the net metabolic power and v is the swimming speed. The contribution of the aerobic and anaerobic energy sources to E in swimming competitions is independent of swimming style, gender or skill and depends essentially upon the duration of the exercise. C(sw) is ess...

The aim of this paper was to develop a model from experimental data allowing a prediction of the cardiopulmonary responses to steady-state submaximal exercise in varying gravitational environments, with acceleration in the Gz axis (a g) ranging from 0 to 3 g. To this aim, we combined data from three different experiments, carried out at Buffalo, at...

Physiological adjustments and passive thermal insulation are not sufficient to protect divers in the cold and warm waters experienced by sport, professional and military divers. In a previous study of resting subjects, divers were protected by actively heated/cooled water that perfused a six-zone (head, torso, arms, hands, legs and feet) tube suit....

Portable underwater electrical power is needed for many commercial, recreational and military applications. A battery system is currently not available to meet these needs, which was the aim of this project. Lithium-ion battery cells (Panasonic (CGR18650E)) were chosen, based on their high energy density and availability. To increase their voltage,...

The energy cost per unit distance (i. e. the economy of swimming, C) is given by the ratio Ē / v where Ē is the net (above resting) metabolic power and v is the swimming speed. The contribution of the aerobic and anaerobic energy sources to Ē in swimming competitions differs according to the distance covered; it is independent of swimming style, ge...

There is no consensus on the best diet for exercise, as many variables influence it. We propose an approach that is based on the total energy expenditure of exercise and the specific macro- and micronutrients used. di Prampero quantified the impact of intensity and duration on the energy cost of exercise. This can be used to determine the total ene...

Cerebral autoregulation (CA) maintains cerebral blood flow (CBF) constant over a wide range of perfusion pressures (MAP). However, arterial PCO 2 (P ET CO 2 ) may modify CBF if brain metabolism and total oxygen consumption (VO 2 ) are modified. During exercise MAP, VO 2 and VCO 2 are increased and may affect CBF. Female (13) and male (9) subjects c...

Underwater workers, sport and military divers, are exposed to thermal stress since most of the waters of the world are below or above what is thermally neutral. Although divers wear insulation suits for passive thermal protection they are inadequate. Active heating is currently accomplished by resistive heating and open-flow tubes delivering hot wa...

Resistance respiratory muscle training (RRMT) increases respiratory muscle and swimming performance at depths down to 17 msw. It is unknown if RRMT improves swimming performance at greater depths and if the improvements are associated with a reduced work of breathing (WOB), altered respiratory mechanics and/or improved respiratory muscle performanc...

To evaluate the safety and effectiveness of subsymptom threshold exercise training for the treatment of post-concussion syndrome (PCS). Prospective case series. University Sports Medicine Concussion Clinic. Twelve refractory patients with PCS (6 athletes and 6 nonathletes). Treadmill test to symptom exacerbation threshold (ST) before and after 2 to...

Obese Zucker rats have more collapsible isolated upper airways, compared with their lean counterparts. The functional characteristics of the tongue as a potential mechanism for the enhanced upper airway collapsibility in the obese Zucker rat are unknown. This study measured the functional characteristics of the tongue muscle in lean and obese Zucke...

Maximal performance in swimming depends on metabolic power and the economy of swimming. Thus, the energy cost of swimming (economy= VO(2)/V, C(s)) and maximal aerobic power (VO(2max)) in elite young female swimmers (n=10, age: 15.3+/-1.5 years) and their relationships to race times (50-1,000 m) and national ranking were examined. VO(2) increased ex...

The aim of this study was to investigate the role of trunk incline (TI) and projected frontal area (A(eff)) in determining drag during active/passive measurements. Active drag (D(a)) was measured in competitive swimmers at speeds from 0.6 to 1.4 m s(-1); speed specific drag (D(a)/v(2)) was found to decrease as a function of v (P < 0.001) to indicat...

Human exposure to the challenges of the underwater world has been traced back thousands of years. However, the last century has seen an acceleration of activities with disparate foci on the "Silent World". The variety and beauty of marine life attract recreational divers and the pressing need for exploitation of new energy sources have led to techn...

Water covers over 75% of the earth, has a wide variety of depths and temperatures, and holds a great deal of the earth's resources. The challenges of the underwater environment are underappreciated and more short term compared with those of space travel. Immersion in water alters the cardio-endocrine-renal axis as there is an immediate translocatio...

The objective of this Postdoctoral fellowship was to provide education to extend their training to embarking on an independent research. Two Postdoctoral Fellows were trained. Important safety issues of breath-holding and limitations to diver performance were studied. Two studies showed the potential for increased risk of loss of consciousness (LOC...

Missions in cold and hot water have to be planned to insure thermal protection to prevent loss of diver capability. The objective of this project was to design, develop and test a diver thermal protection system (DTPS) that would eliminate the thermal constraint, and protect free swimming divers in waters from 5C to 40C at rest and during exercise...

Respiratory muscle training (RMT) has been shown to improve divers swimming endurance at 4 feet of depth; however, its effectiveness at greater depths, where gas density and the work of breathing are substantially elevated has not been studied. The purpose of this study was to examine the effects of resistance respiratory muscle training (RRMT) on...

Passive insulations alone are not sufficient for maintaining underwater divers in thermal balance or comfort. The purpose of this study was to experimentally determine the active heating and cooling requirements to keep a diver at rest in thermal balance and comfort in water temperatures between 10 and 40 °C. A diver wearing a prototype tubesuit an...

Underwater swimming is a unique exercise and its fitness is not accomplished by other types of training. This study compared high intensity intermittent fin-swim training (HIIT) with moderate intensity continuous (MICT). Divers (n = 20; age = 23 +/- 4 yrs; weight = 82.57 +/- 10.38 kg; height = 180 +/- 6 cm) were assigned to MICT (65%-75% heart rate...

Breath holding is normally terminated due to the urge to breathe, mainly caused by the increasing carbon dioxide level. It was recently shown that a combination of 18 h of carbohydrate-free diet and prolonged exercise prior to breath holding lowered the respiratory exchange ratio (RER) and end-expiratory PO(2 )at maximal breath-hold break-point (MB...

Cholesterol lowering drugs are associated with myopathic side effects in 7% of those on therapy, which is reversible in most, but not all patients. This study tested the hypothesis that total body fat oxidation (TBFO) is reduced by statins in patients with genetic deficiencies in FO, determined by white blood cells (FOwbc) and by molecular analysis...

The active heating/cooling requirements to thermally sustain a human subject submerged in 10, 20, 30 and 40 °C water was measured using a system that circulated water through a zoned tubesuit garment. Water at 30 °C was circulated through the garment at a flow rate of about 0.5 L/min to each of six body regions and the outlet temperatures were meas...

Respiratory work is increased during exercise under water and may lead to respiratory muscle fatigue, which in turn can compromise swimming endurance. Previous studies have shown that respiratory muscle training, conducted five days per week for four weeks, improved both respiratory and fin swimming endurance. This training (RRMT-5) consisted of in...

The effects of voluntary isocapnic hyperpnea (VIH) training (10 h over 4 weeks, 30 min/day) on ventilatory system and running performance were studied in 15 male competitive runners, 8 of whom trained twice weekly for 3 more months. Control subjects (n = 7) performed sham-VIH. Vital capacity (VC), FEV1, maximum voluntary ventilation (MVV), maximal...

Respiratory muscles can fatigue during prolonged and maximal exercise, thus reducing performance. The respiratory system is challenged during underwater exercise due to increased hydrostatic pressure and breathing resistance. The purpose of this study was to determine if two different respiratory muscle training protocols enhance respiratory functi...

Aerogel is among the best solid thermal insulators. Aerogel is a silica gel formed by supercritical extraction which results in a porous open cell solid insulation with a thermal conductivity as low as 0.013 W/m K. Aerogels have a wide range of uses such as insulation for windows, vehicles, refrigerators/freezers, etc. Usage for aerogel can be exte...

Although most patients with concussion recover within days to weeks, a small but significant minority develop persistent signs and symptoms of post-concussion syndrome (PCS). The standard treatments of PCS, rest and cognitive adaptation, have limited effectiveness. PCS patients are advised not to exercise because of the concern for symptom exacerba...

Typically, ventilation is tightly matched to CO2 production. However, in some cases CO2 is retained (SCUBA diving). One factor behind hypoventilation in divers may be low respiratory CO2 sensitivity. If this is due to inadequate respiratory muscle performance it might be remedied by respiratory muscle training (RMT). We retrospectively investigated...

The purpose of this study was to compare the thermal resistance of a wetsuit fabricated from aerogel-syntactic foam hybrid insulation developed by Bardy et al [1] to a foam neoprene wetsuit. The thermal resistance of the hybrid wetsuit and a foam neoprene wetsuit was measured on a human test subject in water at 0.25 MPa (15.25 msw) of hyperbaric pr...

A method is described for the recording a swimmer’s velocity and synchronizing these records with the underwater video. Examples of these records during pushing off from the side of the pool, breaststroke, butterfly stroke, backstroke, and crawl stroke are presented. These records demonstrate to swimmers and coach the bio-mechanics of swimming,...

Performance is the time (t) to cover a given distance (d), i. e. speed of swimming (v = d / t). In turn, v is the product of stroke rate (SR), and distance per stroke (d/S). Maximal v is set by maximal metabolic power (E’ max ) and energy cost of swimming (C s ). Drag (D), efficiency ( h ) and v set the metabol- ic requirements. D can be partitione...

This study investigated the basic fluid mechanics associated with the hydrodynamic drag of a human. The components of drag (frictionD SF, pressureD P and waveD W) on a human swimmer were analysed by applying classical fluid dynamic fundamentals. General methods of reducing drag were considered and the most probable method identified, applied and te...

The purpose of this study was to present a new underwater thermal insulation designed for flexibility and high thermal resistance. The insulation was a hybrid composite of two constituents: syntactic foam and an insulating aerogel blanket. Methods for treating and combining the constituents into a hybrid insulation of several designs are presented....

The aim of this study was to investigate how fins with varying physical characteristics affect the energy cost and the efficiency of aquatic locomotion. Experiments were performed on ten college swimmers who were asked to swim the dolphin kick while using a monofin (MF) and to swim the front crawl kick with a small-flexible fin (SF), a large-stiff...

Objectives: To determine whether a low fat diet supplemented with omega-3 positively affects quality of life (QOL) in relapsing-remitting MS (RRMS) patients. In this 1-year long double-blind, randomized trial, patients were randomized to two dietary interventions: the "Fish Oil" (FO) group received a low fat diet (15% fat) with omega-3 FOs and the...

Licensed Innovation - TYR Aqua Shift, performance swimwear developed for the 2004 Olympic Games, uses patent pending swim technology based on a University at Buffalo innovation that improves swimming performance by altering the fluid dynamics of water as it flows over and around a swimmer

The purpose of this study was to show that the thermal properties of foam neoprene under hydrostatic pressure cannot be predicted by theoretical means, and that uni-axial pressure cannot simulate hydrostatic compression. The thermal conductivity and compressive strain of foam neoprene were measured under hydrostatic pressure. In parallel, uni-axial...

With the aim of computing a complete energy balance of front crawl, the energy cost per unit distance (C = Ev(-1), where E is the metabolic power and v is the speed) and the overall efficiency (eta(o) = W(tot)/C, where W(tot) is the mechanical work per unit distance) were calculated for subjects swimming with and without fins. In aquatic locomotion...

The effect of fat intake on total body (TB) and white blood cell (WBC) fat oxidation (FO) was studied during exercise in sedentary subjects. Four men and 6 women consumed diets of 19% and 50% energy from fat for 3 weeks each compared with their regular diet (30%). Before and after each diet, TB FO was measured at each stage of a treadmill test and...

This research was theoretical and experimental, with an objective of a better understanding of the physics of fin swimming. The theoretical work followed Lighthill’s slender body theory (1960). Video measurements were made on underwater fin swimmers swimming in an annular pool (58.6 m in circumference). This study considers only SCUBA divers. Five...

Propulsion in water requires a propulsive force to overcome drag. Male subjects were measured for cycle frequency, energy cost and drag (D) as a function of velocity (V), up to maximal V, for fin and front crawl swimming, kayaking and rowing. The locomotion with the largest propulsive arms and longest hulls traveled the greatest distance per cycle...

Osteoarthritis (OA) is a common and debilitating disease that often affects the knees. Patients suffer from pain and disability and have associated reductions in muscle and cardiopulmonary function. We quantitatively evaluated the effects of an 8-week water exercise program (WEP) on muscle, cardiovascular, and functional capacity on patients with k...

Dietary fat intake and exercise affect the immune system. This study determined the changes in inflammatory components of the immune system in response to maximal exercise with three levels of dietary fat intake: 19%, 30%, and 50% of total calories. Five men and six women were randomly assigned to consume diets with 19% and 50% calories from fat fo...

The drag (D) of seven (7) male swimmers wearing five (5) swimsuits was investigated. The drag was measured during passive surface tows at speeds from 0.2 up to 2.2 m x s and during starts and push-offs. The swimsuits varied in body coverage from shoulder-to-ankle (SA), shoulder-to-knee (SK), waist-to-ankle (WA) and waist-to-knee (WK) and briefs (CS...

Cardiac output (Q) is a determinant of blood pressure and O(2) delivery and is critical in the maintenance of homeostasis, particularly during environmental stress and exercise. Cardiac output can be determined invasively in patients; however, indirect methods are required for other situations. Soluble gas techniques are widely used to determine (Q...

The desired level of dietary fat intake is controversial. The effect of decreasing fat intake to 19% and increasing it to 50% from a control diet of 30% on nutritional status and cardiovascular risk factors in healthy individuals was studied. Eleven healthy subjects (5 men and 6 women) were randomized to consume diets with 19% and 50% calories from...

Fat oxidation is important for maintaining health and for supplying energy for exercise. We have proposed that the predisposition for individual rates of fat oxidation is determined genetically but may be modulated by acute exercise or exercise training. The purpose of this study was to examine cellular fat oxidation in white blood cells (WBC) usin...

Fat oxidation is important for maintaining health and for supplying energy for exercise. We have proposed that the predisposition for individual rates of fat oxidation is determined genetically but may be modulated by acute exercise or exercise training. The purpose of this study was to examine cellular fat oxidation in white blood cells (WBC) usin...

In this paper a complete energy balance for water locomotion is attempted with the aim of comparing different modes of transport in the aquatic environment (swimming underwater with SCUBA diving equipment, swimming at the surface: leg kicking and front crawl, kayaking and rowing). On the basis of the values of metabolic power (E), of the power need...

Cardiac output (Q) is a primary determinant of blood pressure and O2 delivery and is critical in the maintenance of homeostasis, particularly during environmental stress. Cardiac output can be determined invasively in patients; however, indirect methods are required for other situations. Soluble gas techniques are widely used to determine Q. Histor...

An analytical solution is presented for the steady-periodic shape variation of a thin elastic beam subject to fluid mechanic forces and driven by the motion imposed on its ends. The general solution is applicable to such problems as swim fins and aerodynamic flutter, with the proper choice of boundary conditions. The general results are exemplified...

Underwater swimmers use fins which augment thrust to overcome drag and propel the diver. The VdotO2 of swimming as a function of speed, velocity as a function of kick frequency, maximal speed (v), maximal oxygen consumption (VdotO2) and the maximal thrust were determined for eight fins in 10 male divers swimming at 1.25 m depth in a 60 m annular po...

Underwater swimmers use fins, which provide thrust to overcome drag and propel the diver. The type of fin used has been shown to affect diver performance, however data are lacking for women. The oxygen consumption (VdotO2) of swimming as a function of speed, velocity as a function of kick frequency, maximal speed (v), maximal VdotO2 and the maximal...

Carnitine palmitoyltransferase (CPT) II deficiency disorders are clinically very variable. To examine the cause(s) of variable symptoms in first-degree relatives with CPT II deficiency, four sisters with various combinations of mutations and polymorphisms in the CPT2 gene were studied, together with 20 sedentary and 24 trained healthy female subjec...

The aim of the present study was to quantify the improvements in the economy and efficiency of surface swimming brought about by the use of fins over a range of speeds (v) that could be sustained aerobically. At comparable speeds, the energy cost (C) when swimming with fins was about 40 % lower than when swimming without them; when compared at the...

The effects of an intense 8-wk aerobic training program on cardiovascular responses at rest and during exercise, including heart rate variability (HRV) as an expression of autonomic modulation, were evaluated in subjects over 70 yr (mean: 73.9 +/- 3.5 yr). Before and after training in 7 men and 8 women: a) heart rate (HR), blood pressures (BPs), pu...