Allan Hahn - Profile on Academia.edu (original) (raw)

Papers by Allan Hahn

Plasma Ferritin Concentration and Physical Work Capacity in Athletes

International Journal of Sport Nutrition, Dec 1, 1992

This investigation aimed to determine whether the physical work capacity of nonanemic athletes co... more This investigation aimed to determine whether the physical work capacity of nonanemic athletes could be improved when plasma ferritin concentrations of below 30 nglml were raised at least 15 ng/ml. The experimental group consisted of 15 training athletes, each of whose plasma ferritin concentration was less than 30 ng/ml (mean and SD of 19.8 ±8.4 nglml). In a control group of 16, each was measured with a plasma ferritin concentration of more than 40 ng/ml (mean and SD of 83.3 ±37.6 ngfml). All participated in submaximal and maximal tests for aerobic and anaerobic power. Following iron supplementation, plasma fenitin concentration in each experimental subject increased by at least 15 nglml to more than 30 ng/ml, to a new mean of 46.3 ±15.5 ng/ml. The performance measures were also repeated, but no significant overall effects were associated with the increased plasma ferritin concentrations. These data provide no sound evidence that physical work capacity of athletes is enhanced when plasma ferritin concentrations of around 20 ng/ml are increased by at least 15 ng/ml.

British Journal of Sports Medicine, Sep 1, 1998

Iron deficiency anaemia, and its debilitating eVect on performance, is an area of concern for man... more Iron deficiency anaemia, and its debilitating eVect on performance, is an area of concern for many female athletes. Automated technologies that analyse individual reticulocytes may provide a sensitive measure of bone marrow response to iron supplementation. The reticulocyte characteristics of a female volleyball player with frank iron deficiency anaemia, and her subsequent response to oral iron therapy, are reported.

International Journal of Sport Nutrition and Exercise Metabolism, Sep 1, 2001

β-Hydroxy β-methylbutyrate (HMB), a metabolite of the essential amino acid leucine, is one of the... more β-Hydroxy β-methylbutyrate (HMB), a metabolite of the essential amino acid leucine, is one of the latest dietary supplements promoted to enhance gains in strength and lean body mass associated with resistance training. Unlike anabolic hormones that induce muscle hypertrophy by increasing muscle protein synthesis, HMB is claimed to influence strength and lean body mass by acting as an anticatabolic agent, minimising protein breakdown and damage to cells that may occur with intense exercise. Research on HMB has recently tested this hypothesis, under the assumption that it may be the active compound associated with the anticatabolic effects of leucine and its metabolites. While much of the available literature is preliminary in nature and not without methodological concern, there is support for the claims made regarding HMB supplementation, at least in young, previously untrained individuals. A mechanism by which this may occur is unknown, but research undertaken to date suggests there may be a reduction in skeletal muscle damage, although this has not been assessed directly. The response of resistance trained and older individuals to HMB administration is less clear. While the results of research conducted to date appear encouraging, caution must be taken when interpreting outcomes as most manuscripts are presented in

Características Fisiológicas de Ciclistas Profesionales de Mountain Bike y de Ruta Exitosos - International Endurance Group

PubliCE, 2014

International Journal of Performance Analysis in Sport, Dec 1, 2005

Beneficios Potenciales de las Chaquetas Refrigerantes

PubliCE Standard, May 15, 2005

Los científicos del Instituto Australiano del Deporte han desarrollado una chaqueta para el pre e... more Los científicos del Instituto Australiano del Deporte han desarrollado una chaqueta para el pre enfriamiento de los atletas antes de eventos de resistencia en ambientes calurosos. Las chaquetas están hechas de un material que no permite el paso de la humedad y se rellenan con ...

Journal of Science and Medicine in Sport, 2009

There is conflicting evidence whether hypoxia improves running economy (RE), maximal O 2 uptake (... more There is conflicting evidence whether hypoxia improves running economy (RE), maximal O 2 uptake (V O 2 max), haemoglobin mass (Hb mass) and performance, and what total accumulated dose is necessary for effective adaptation. The aim of this study was to determine the effect of an extended hypoxic exposure on these physiological and performance measures. Nine elite middle distance runners were randomly assigned to a live high-train low simulated altitude group (ALT) and spent 46 ± 8 nights (mean ± S.D.) at 2860 ± 41 m. A matched control group (CON, n = 9) lived and trained near sea level (∼600 m). ALT decreased submaximalV O 2 (L min −1) (−3.2%, 90% confidence intervals, −1.0% to −5.2%, p = 0.02), increased Hb mass (4.9%, 2.3-7.6%, p = 0.01), decreased submaximal heart rate (−3.1%, −1.8% to −4.4%, p = 0.00) and had a trivial increase inV O 2 max (1.5%, −1.6 to 4.8; p = 0.41) compared with CON. There was a trivial correlation between change in Hb mass and change inV O 2 max (r = 0.04, p = 0.93). Hypoxic exposure of ∼400 h was sufficient to improve Hb mass , a response not observed with shorter exposures. Although total O 2 carrying capacity was improved, the mechanism(s) to explain the lack of proportionate increase inV O 2 max were not identified.

European journal of applied physiology and occupational physiology, Sep 1, 1999

The purpose of this study was to document the eect of 23 days of``live high, train low'' on the h... more The purpose of this study was to document the eect of 23 days of``live high, train low'' on the haemoglobin mass of endurance athletes. Thirteen male subjects from either cycling, triathlon or crosscountry skiing backgrounds participated in the study. Six subjects (HIGH) spent 8A10 h per night in a``nitrogen house'' at a simulated altitude of 3000 m in normobaric hypoxia, whilst control subjects slept at near sea level (CON-TROL, n = 7). Athletes logged their daily training sessions, which were conducted at 600 m. Total haemoglobin mass (as measured using the CO-rebreathing technique) did not change when measured before (D1 or D2) and after (D28) 23 nights of hypoxic exposure [HIGH 990 (127) vs 972 (97) g and CONTROL 1042 (133) vs 1033 (138) g, before and after simulated altitude exposure, respectively]. Nor was there any dierence in the substantial array of reticulocyte parameters measured using automated¯ow cytometry prior to commencing the study (D1), after 6 (D10) and 15 (D19) nights of simulated altitude, or 1 day after leaving the nitrogen house (D28) when HIGH and CONTROL groups were compared. We conclude that red blood cell production is not stimulated in male endurance athletes who spend 23 nights at a simulated altitude of 3000 m.

Journal of Science and Medicine in Sport, Mar 1, 2005

Technological foundations and current status of a modified, low-risk form of competitive boxing (Box'Tag®)

Sports Technology, Aug 1, 2011

Boxing-related activities are commonly used for fitness enhancement, but for many people fear of ... more Boxing-related activities are commonly used for fitness enhancement, but for many people fear of injury precludes participation in competitive boxing. Over the past six years, technological developments have contributed to the emergence in Australia of a modified, low-risk form of competitive boxing called Box'Tag®. The rules of Box'Tag® prohibit impacts to the head and any impacts above a moderate level of force. Contestants wear instrumented equipment that, in combination with a dedicated software package, allows automated impact detection and real-time display of scores. Participatory action research methods are being used to guide iterative technology refinements, with success evaluated based on feedback obtained through constant, direct interaction with the technology end-users. In concert with technological advances, the popularity of Box'Tag® is steadily increasing, with programmes now established in three Australian states and about to be initiated elsewhere. Box'Tag® is attracting demographically diverse participation and injury rates are low. Physiological and perceptual data recorded during contests show Box'Tag® to be a highly intensive activity and an excellent vehicle for building physical fitness. There is scope for further technological improvements, but the Box'Tag® initiative is already demonstrating potential to add a new dimension to boxing and has been adopted by Australian boxing authorities.

$Research paper thumbnail of Absence of refractoriness in asthmatic subjects after exercise with warm, humid inspirate$

Thorax, Jun 1, 1985

Twelve asthmatic adults each completed two six minute treadmill runs separated by an interval of ... more Twelve asthmatic adults each completed two six minute treadmill runs separated by an interval of 20 minutes. Running speed was constant for each subject, and inspired air temperature averaged 5.5°C (SD 1.5°) for both tests. Total minute ventilation and total respiratory heat loss showed no significant difference between the two runs. Forced expiratory volume in one second (FEV,) was measured before exercise and at five minute intervals throughout the recovery periods, during which subjects breathed room air at an average temperature of 1 7.8°C (1.80).

A simple method for the assessment of general fitness: The Tri-level Profile

The Australian journal of science, 1989

trained distance runners performance or erythropoietic markers in highly Intermittent normobaric hypoxia does not alter

Increased arterial desaturation in trained cyclists during maximal exercise at 580 m altitude

Journal of Applied Physiology, 1996

This study utilized a hypobaric chamber to compare the effects of mild hypobaria (MH; 50 mmHg, ap... more This study utilized a hypobaric chamber to compare the effects of mild hypobaria (MH; 50 mmHg, approximately 580 m altitude) on blood O2 status and maximal O2 consumption (VO2max) in 9 untrained and 11 trained (T) cyclists with VO2max values of 51 +/- 3 and 77 +/- 1 ml.kg-1.min-1, respectively. In both groups, arterial O2 saturation (SaO2) decreased significantly during maximal exercise, and this effect was enhanced with MH. Both these responses were significantly greater in the T cyclists in whom the final SaO2 during MH was 86.5 +/- 0.9%. When the group data were combined, approximately 65% of the variance in SaO2 could be attributed to a widened alveolar-arterial Po2 difference. The arterial PO2 during maximal exercise at sea level in the T group was on the steeper portion of the hemoglobin-O2-loading curve (T, 68.3 +/- 1.3 Torr; untrained, 89.0 +/- 2.9 Torr) such that a similar decrease in arterial PO2 in the two groups in response to MH resulted in a significantly greater fall ...

Journal of Applied Physiology, 2002

There is a wide body of literature reporting red cell hemolysis as occurring after various forms ... more There is a wide body of literature reporting red cell hemolysis as occurring after various forms of exercise. Whereas the trauma associated with footstrike is thought to be the major cause of hemolysis after running, its significance compared with hemolysis that results from other circulatory stresses on the red blood cell has not been thoroughly addressed. To investigate the significance of footstrike, we measured the degree of hemolysis after 1 h of running. To control for the potential effects of oxidative and circulatory stresses on the red blood cell, the same subjects cycled for 1 h at equivalent oxygen uptake. Our subjects were 10 male triathletes, who each completed two separate 1-h sessions of running and cycling at 75% peak oxygen uptake, which were performed in random order 1 wk apart. Plasma free hemoglobin and serum haptoglobin concentrations were measured as indicators of hemolysis. We also measured methemoglobin as a percentage of total hemoglobin immediately postexer...

One hundred and fifty years of rowing faster

$Research paper thumbnail of Histamine reactivity during the refractory period after exercise induced asthma$

Thorax, 1984

An episode of exercise induced asthma will usually be followed by a period during which further e... more An episode of exercise induced asthma will usually be followed by a period during which further exercise will not induce asthma. Postulated mechanisms include persistence of catecholamines released during exercise, development of tolerance to released mediators, and mediator depletion. To investigate the underlying mechanism further eight asthmatic men underwent three experimental protocols as follows: two treadmill runs of eight minutes; two incremental challenges with histamine inhalation; and a treadmill run of eight minutes followed by an incremental challenge with histamine inhalation. In each case the two challenges began 40 minutes apart. Patients performed the paired exercise trial first. Refractoriness to bronchoconstriction was shown in the repeated exercise studies but did not occur with repeated histamine challenge. The geometric mean histamine concentrations required to produce a 20%

VO2max & ARTERIAL O2 SATURATION AT SEA LEVEL & 610 m

Medicine & Science in Sports & Exercise, 1995

Does Intermittent Normobaric Hypoxic Exposure Uncouple Submaximal &OV0312;O2 and Power?

Medicine & Science in Sports & Exercise, 1999