Terje Gjøvaag - Academia.edu (original) (raw)

Papers by Terje Gjøvaag

Research paper thumbnail of Oxygen Uptake and Energy Expenditure during Treadmill Walking with Masai Barefoot Technology (MBT) Shoes

Journal of Physical …, Jan 1, 2011

Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase ox... more Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase oxygen uptake and result in greater consumption of energy relative to walking with conventional shoes, but this has not been sufficiently investigated. [Methods] To examine this supposition, ten subjects walked on a treadmill with different types of shoes (jogging or MBT shoes), treadmill inclinations (zero or 10 % inclination) and walking speeds (i.e. selfselected walking speed or fast walking speed). Oxygen uptake, heart rate, lung ventilation, ratings of perceived exertion and energy expenditure were measured during all walking conditions by a stationary metabolic cart.

Research paper thumbnail of Hemodynamic responses to resistance exercise in patients with coronary artery disease

Purpose: Investigate hemodynamic responses of resistance exercise (RE) with moderate load (i.e. i... more Purpose: Investigate hemodynamic responses of resistance exercise (RE) with moderate load (i.e. international guidelines for RE of patients) versus RE with high load in patients with coronary artery disease (CAD).

Research paper thumbnail of The preferred walking speed of unilateral transfemoral amputees is not similar to their most economical walking speed

The preferred walking speed of unilateral transfemoral amputees is not similar to their most econ... more The preferred walking speed of unilateral transfemoral amputees is not similar to their most economical walking speed Background: The quantitative relationship between the walking economy (Cw) and speed of walking during floor and treadmill walking is little investigated in unilateral transfemoral amputees (TFA). In addition, it is still debated whether the preferred walking speed (PWS) of TFA and healthy subjects (CON) is similar to their most economical walking speed (ECOws). Aim: Investigate the energy-speed relationship and ECOws of a group of TFA and CON during level walking on the treadmill and on the floor. Method: A group of TFA (n=8) and a group of CON (n=8) were recruited to the study. Oxygen uptake (VO2) was measured at steady state conditions by a portable oxygen analyzer (Cortex Metamax 3B, Germany) when walking along a 40 meter indoor track and on a treadmill. Both the TFA and CON walked on the two surfaces with five different speeds in random order. Walking speeds wer...

Research paper thumbnail of Hemodynamic responses to high intensity resistance training in patients with ischemic heart disease

Purpose Investigate the hemodynamic responses of resistance training (RT) with moderate load and ... more Purpose Investigate the hemodynamic responses of resistance training (RT) with moderate load and 15 repetitions versus RT with high load and 4 repetitions in patients with ischemic heart disease (IHD). Methods Fifteen medical stable males (n=11) and females (n=4) with IHD treated with PCI or coronary artery bypass graft surgery > six months ago (Table 1) were randomly allocated to test 1 and test 2 (Figure 1). All exercises were performed without breathing holding (Valsava maneuver). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were monitored before and continuously during each session. The hemodynamic status was assessed by impedance cardiography (PhysioFlow Enduro, Manatec, Folschviller, France)

Research paper thumbnail of Effecy of moderate and high intensity intermittent endurance exercise on post exercise hypotension

Research paper thumbnail of Skeletal muscle metabolism in poststroke patients during walking

Background: Is widely accepted that the central nervous system selects the preferred walking spee... more Background: Is widely accepted that the central nervous system selects the preferred walking speed (PWS) to minimize energy expenditure (EE). To conserve limited stores of carbohydrate (CHO) in the body, it is hypothesized that the PWS is most economical under conditions when CHO oxidation is restrained and fat oxidation is favored. Aim: To investigate the EE through measurements of the respiratory exchange ratio (RER) and rates of fat and CHO oxidation in relation to the total energy expenditure (TEE) during overground walking at the PWS. Method: The sample consisted of nineteen subacute stroke patients (mean age 72.6 ± 10.3 years ; body mass index (BMI) 26.1± 2.9; PWS 1.07±0.3 m/sec-1) and nine control subjects (mean age 71.2± 10.2 years; BMI 25.1±5.6; PWS 1.49±0.2 m/sec-1). Each subject walked for 7 minutes at their PWS around a 20 meter length rectangular room using a portable gas analyzer. Measurements of oxygen consumption and carbon dioxide production were recorded. Results: ...

Research paper thumbnail of The oxygen cost of walking is not a good measure for quantifying the physical effort of prosthetic ambulation

The oxygen cost of walking is not a good measure for quantifying the physical effort of prostheti... more The oxygen cost of walking is not a good measure for quantifying the physical effort of prosthetic ambulation Background The oxygen uptake (VO2) during walking is widely recognized as a measure of the whole body energy expenditure, while the oxygen cost of walking (Cw; ml kg

Research paper thumbnail of A review of the role of the partial pressure of carbon dioxide in mechanically loaded tissues: the canary in the cage singing in tune with the pressure ulcer mantra

Annals of biomedical engineering, 2015

Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distr... more Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distribution of pressure over a prolonged period. They can have devastating effects on the patients' well-being and in extreme conditions can prove fatal. In addition to traditional wisdom implicating mechanically induced ischaemia, there is strong evidence that other mechanisms play a role in the cascade of events which can initiate the PU damage process at the cellular level. Some of these refer to a metabolic imbalance with compromised delivery of nutrients and accumulation of waste products in the local environment of the cells. The approach of much research has focused on the measure of oxygen in compressed tissues as a means of predicting early damage. However, the present review adopting a hierarchical approach, using length scales ranging from cells through to human models, has revealed compelling evidence which highlights the importance of carbon dioxide levels and associated con...

Research paper thumbnail of Resistance exercise and acute blood pressure responses

The Journal of sports medicine and physical fitness, Jan 20, 2015

Compare the acute hemodynamic and cardiovascular responses of high load/low repetition resistance... more Compare the acute hemodynamic and cardiovascular responses of high load/low repetition resistance training (RT) to low load/high repetition RT. Thirteen healthy men performed four sets of 4 repetition maximum (RM) and 20RM leg--extensions without breath--holding. The RT was conducted in a randomized order and with 48 hours between bouts. Non--invasive beat--to--beat systolic and diastolic blood--pressure (SBP/DBP) was measured on the finger, while non--invasive cardiac output (CO) was assessed beat--to--beat by impedance--cardiography. Mean ± SD resting SBP/DBP and CO were 126 ± 14/73 ± 9 mmHg and 5.6 ± 9 L min --1 , respectively. Exercise SBP/DBP values increased to 154 ± 22/99 ±18 and 203 ± 33/126 ± 19 mmHg following 4RM and 20RM RT, respectively (compared to rest, all;; p < 0.001), and 20RM SBP/DBP values were higher than 4RM values (both, p < 0.001). The SBP increased from the first to the fourth set of exercise following the 20RM load (p < 0.01), but not so for the 4RM...

Research paper thumbnail of Energy expenditure of transfemoral amputees walking on a horizontal and tilted treadmill simulating different outdoor walking conditions

Prosthetics and Orthotics International, 2010

Background and aim: Transfemoral amputees often report that walking on tilted pavements or in ter... more Background and aim: Transfemoral amputees often report that walking on tilted pavements or in terrain with the prosthesis on the highest side is quite strenuous. This study investigates the energy expenditure of transfemoral amputees (n=8) walking on altered treadmill positions simulating different outdoor walking conditions. Method: Oxygen uptake at self selected speed of gait was measured during walking at three different treadmill positions: (I) Horizontal treadmill, (II) 3 % tilt in the sagittal plane and (III) 3 % tilt in both the sagittal and frontal plane of the treadmill.

Research paper thumbnail of Assessment of aerobic capacity and walking economy of unilateral transfemoral amputees

Prosthetics and Orthotics International, 2014

Studies of the maximal oxygen uptake (VO(2max)) of transfemoral amputees have mostly used protoco... more Studies of the maximal oxygen uptake (VO(2max)) of transfemoral amputees have mostly used protocols that activate a relatively small muscle mass. Consequently, transfemoral amputee VO(2max) may be systematically underestimated, and the validity of these test protocols is questionable. (1) Investigate validity and reliability of a VO(2max) walking protocol and (2) compare the VO(2max) of a transfemoral amputee group with a group of matching controls. (1) Randomized crossover study: walking versus running VO(2max) for the control group and (2) case-control study: transfemoral amputees versus control group VO(2max). Twelve transfemoral amputees and control participants performed a walking VO(2max) test with increasing treadmill inclinations to voluntary exhaustion. The control group also completed a running (&quot;gold-standard&quot;) VO(2max) test. Mean (standard deviation) control group VO(2max) following walking and running was similar, that is, 2.99 (0.6) L min(-1) and 3.09 (0.7) L min(-1), respectively. Mean (standard deviation) transfemoral amputee walking VO(2max) was 2.14 (0.8) L min(-1) (compared to CON; p &lt; 0.01). Mean intraclass correlation coefficient of repeated VO(2) measurements was 0.97, and within-subjects standard deviation was 60 mL min(-1). The walk protocol is valid. Walking VO(2max) of transfemoral amputees was 40% lower compared to control group. Reliability of the walking protocol is comparable to other walking protocols. Clinical relevance The design, alignment, and materials of prostheses are important for effective ambulation. Cardio-respiratory fitness is, however, also important in this regard, and a low fitness may compromise health and independent living. Hence, transfemoral amputees with low physical fitness should engage in regular physical activity to improve health, gait capacity, and independency.

Research paper thumbnail of Oxygen Uptake and Energy Expenditure during Treadmill Walking with Masai Barefoot Technology (MBT) Shoes

Journal of Physical Therapy Science, 2011

Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase ox... more Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase oxygen uptake and result in greater consumption of energy relative to walking with conventional shoes, but this has not been sufficiently investigated. [Methods] To examine this supposition, ten subjects walked on a treadmill with different types of shoes (jogging or MBT shoes), treadmill inclinations (zero or 10 % inclination) and walking speeds (i.e. selfselected walking speed or fast walking speed). Oxygen uptake, heart rate, lung ventilation, ratings of perceived exertion and energy expenditure were measured during all walking conditions by a stationary metabolic cart.

Research paper thumbnail of Novel Design of an Optical Probe for Detecting Perfusion Changes in Buccal Tissue

IEEE Sensors Journal, 2000

Measuring the blood perfusion and microcirculation at a specific depth in human tissue is an impo... more Measuring the blood perfusion and microcirculation at a specific depth in human tissue is an important method to monitor oxygenation in critically ill patients. The optical probes, that are currently available in the market, are not capable of monitoring the blood perfusion from a given tissue layer and at a specific depth. We have designed a novel optical probe which is able to focus the light at a specific depth of ∼670 µm in buccal tissue. The new probe consists of two light guides for sending and detecting the reflected light from the sampling area (tissue), and a lens to focus the light into the desired depth of the tissue and collect it back from the same area. The new optical probe has been compared to a commercial laser Doppler probe by collecting data from the same sampling area. The result from our probe showed 15% higher accuracy in detecting changes in blood perfusion compared with an existing commercial probe.

Research paper thumbnail of Effect of concentric or eccentric weight training on the expression of heat shock proteins in m. biceps brachii of very well trained males

European Journal of Applied Physiology, 2006

Increased HSP expression in response to acute exercise is well documented in animal studies, and ... more Increased HSP expression in response to acute exercise is well documented in animal studies, and there is growing evidence that similar responses occur in man. In general, many human exercise studies have investigated the HSP response to low force continuous activity, while the knowledge about the HSP response to high force intermittent type of activity, like weight training, is so far sparse. In addition, most studies have used untrained subjects, and a common observation is that acute low force continuous activity in untrained individuals increases the HSP expression in these individuals.The main scope of this study was to investigate the HSP response in very well trained males subjected to longitudinal high intensity exercise, and if this response was dependent on exercise modality [i.e. eccentric (ECC) or concentric (CON) contractions]. Very well trained males performed progressive strength training consisting of either high force ECC or high force CON elbow flexions 2-3 times a week for 12 weeks. Compared with preexercise levels, HSP72 expression decreased by 46.1% (P<0.05) after CON contractions. GRP75 expression was unchanged after ECC or CON contractions, while ubiquitin expression decreased by 19.9% (P<0.02) after ECC contractions. These findings imply that chronic, intensive exercise may attenuate the HSP response in well-trained males.

Research paper thumbnail of Effect of training with different intensities and volumes on muscle fibre enzyme activity and cross sectional area in the m. triceps brachii

European Journal of Applied Physiology, 2008

This study primarily examined how intermittent versus continuous endurance training, using simila... more This study primarily examined how intermittent versus continuous endurance training, using similar or dissimilar volumes, aVected muscle Wbre enzyme activities in the triceps brachii muscle. Thirty-two subjects performed either intermittent (60% of 1RM) or continuous (30% of 1RM) elbow extensions 3 times week ¡1 in a training apparatus. Training was performed until either a low (Wve) or a high volume (8 weeks) was accumulated. Muscle biopsies from the m. triceps brachii were taken pre-and post training and following 8 weeks of detraining. Marker enzymes for muscle Wbre oxidative (succinate dehydrogenase SDH) and glycolytic (glycerophosphate dehydrogenase; -GPDH) capacity was assessed by histochemistry, and the resulting enzyme activities measured by image analysis. The type of training aVected enzyme activities diVerently. In type 1 Wbres, continuous and intermittent training was equally eVective in increasing SDH activity, while intermittent training increased SDH activity more than continuous training in type 2 Wbres (P < 0.05). Intermittent training increased -GPDH activity more than continuous training both in type 1 (P < 0.001) and type 2 Wbres (P < 0.05), but the increase in glycolytic capacity following intermittent training was larger in type 1 (54%) than in type 2 Wbres (23%). There was no eVect of training volume on oxidative or glycolytic capacity in either Wbre type. Thus, when training intensity is suYcient to stimulate to increases in oxidative and glycolytic capacity, the SDH and -GPDH response seems to be volume independent. Detraining reduced Post-T enzyme activities to baseline (all; P < 0.01).

Research paper thumbnail of Effect of training and detraining on the expression of heat shock proteins in m. triceps brachii of untrained males and females

European Journal of Applied Physiology, 2006

Forty untrained persons were randomized to four diVerent training protocols that exercised the m.... more Forty untrained persons were randomized to four diVerent training protocols that exercised the m. triceps brachii. Group 1 and 2 performed high intensity (HI) elbow extensions and group 3 and 4 performed low intensity (LI) elbow extensions. Group 1 and 3 trained until they had accumulated a matching high volume (HV) of training, while group 2 and 4 trained until they had accumulated a matching low volume (LV) of training. Training for 5-8 weeks increased the HSP72, HSP27 and GRP75 levels in the subjects' m. triceps brachii by 111, 71 and 192%, respectively ( . There were, however, no signiWcant diVerences in the heat shock protein (HSP) responses to training between the four training groups . The frequency of extreme responses to exercise was, however, higher after HI exercise than after LI exercise, indicating that HI exercise induces extreme HSP reactions in some subjects. When we assigned the subjects to three clusters, according to the total number of repetitions they had lifted, the subjects who had lifted the highest number of repetitions had lower PostExc HSP levels compared with subjects that lifted the low-est number of repetitions ( . Additionally, there was a negative non-linear regression between the subjects PreExc levels of HSP72, HSP27 and GRP75 and the percentage change in their respective protein concentration after training (r = ¡0.75, ¡0.89 and ¡0.88, all P < 0.0001). Thus, the PreExc level of HSPs seems to be an important "regulator" of HSP expression following the training.

Research paper thumbnail of Effect of training on the activity of five muscle enzymes studied on elite cross-country skiers

Acta Physiologica Scandinavica, 1999

This study examines the effect of training intensity on the activity of enzymes in m. vastus late... more This study examines the effect of training intensity on the activity of enzymes in m. vastus lateralis. Elite junior cross-country skiers of both sexes trained 12-15 h weeks-1 for 5 months at either moderate (60-70% of VO2max, MIG) or high training intensity (80-90% of the VO2max, close to the lactate threshold; HIG). Muscle biopsies for enzyme analyses and fibre typing were taken before and after the training period. Histochemical analyses on single fibres were done for three enzymes (succinate dehydrogenase [SDH], hydroxybutyrate dehydrogenase [HBDH], glycerol-3-phosphate dehydrogenase [GPDH]), while the activity of citrate synthase [CS] and phosphofructokinase [PFK] was measured on whole biopsies. The activity of GPDH was low in ST fibres and high in FT fibres. The activity of SDH and HBDH was high in both ST and FTa fibres but low in the FTb fibres. The HIG increased their performance more than the MIG did during the training period as judged from scores on a 20-min run test. The SDH activity rose by 6% for the HIG (P &lt; 0.02). No effects of training were found in the activities of CS, HBDH or GPDH, neither in the two training groups nor for the two genders (P &gt; or = 0.16). The PFK activity fell by 10% for the HIG (P=0.02), while no change was found for the MIG. For GPDH, CS and SDH the women&#39;s activity was approximately 20% less than the value for the men (P &lt; 0.03). For PFK and HBDH there was no sex difference (P &gt; or = 0.27). There were positive correlations between the activity of three of the enzymes (CS, SDH and GPDH) and the performance parameters (VO2max, cross-country skiing and running performance; r &gt; or = 0.6, P &lt; 0.01). No correlations were found between the PFK or HBDH activities and the performance parameters (r &lt; or = 0.16, P &gt; 0.05). This study suggests that intensities near the lactate threshold affect biochemical and physiological parameters examined in this study as well as the performance of elite skiers, and that the rate-limiting enzymes may be more sensitive to training than non-rate-limiting enzymes.

Research paper thumbnail of The physiological responses to repeated upper-body sprint exercise in highly trained athletes

European Journal of Applied Physiology, 2015

sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressi... more sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressively decreased (P < 0.05). m. triceps brachii and m. latissimus dorsi were highly desaturated already after the first sprint (all P < 0.05), whereas the response was delayed for m. biceps brachii and m. vastus lateralis. Correspondingly, increases in VO 2 mainly occurred over the first two sprints (P < 0.05) and plateaued at approximately 75 % of VO 2peak . 1RM correlated with power during the first four sprints and with average sprint power (r = 0.71-0.80, all P < 0.05), whereas VO 2peak correlated with power in the last three sprints (r = 0.60-0.71, all P < 0.05). Conclusions The main decrement in upper-body sprint performance was evident in the first five sprints, followed by highly desaturated muscles and a plateau in pulmonary oxygen uptake already after the first 2-3 sprints. While high maximal strength seems important for producing power, aerobic capacity correlates with power in the last sprints.

Research paper thumbnail of Oxygen Uptake and Energy Expenditure during Treadmill Walking with Masai Barefoot Technology (MBT) Shoes

Journal of Physical …, Jan 1, 2011

Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase ox... more Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase oxygen uptake and result in greater consumption of energy relative to walking with conventional shoes, but this has not been sufficiently investigated. [Methods] To examine this supposition, ten subjects walked on a treadmill with different types of shoes (jogging or MBT shoes), treadmill inclinations (zero or 10 % inclination) and walking speeds (i.e. selfselected walking speed or fast walking speed). Oxygen uptake, heart rate, lung ventilation, ratings of perceived exertion and energy expenditure were measured during all walking conditions by a stationary metabolic cart.

Research paper thumbnail of Hemodynamic responses to resistance exercise in patients with coronary artery disease

Purpose: Investigate hemodynamic responses of resistance exercise (RE) with moderate load (i.e. i... more Purpose: Investigate hemodynamic responses of resistance exercise (RE) with moderate load (i.e. international guidelines for RE of patients) versus RE with high load in patients with coronary artery disease (CAD).

Research paper thumbnail of The preferred walking speed of unilateral transfemoral amputees is not similar to their most economical walking speed

The preferred walking speed of unilateral transfemoral amputees is not similar to their most econ... more The preferred walking speed of unilateral transfemoral amputees is not similar to their most economical walking speed Background: The quantitative relationship between the walking economy (Cw) and speed of walking during floor and treadmill walking is little investigated in unilateral transfemoral amputees (TFA). In addition, it is still debated whether the preferred walking speed (PWS) of TFA and healthy subjects (CON) is similar to their most economical walking speed (ECOws). Aim: Investigate the energy-speed relationship and ECOws of a group of TFA and CON during level walking on the treadmill and on the floor. Method: A group of TFA (n=8) and a group of CON (n=8) were recruited to the study. Oxygen uptake (VO2) was measured at steady state conditions by a portable oxygen analyzer (Cortex Metamax 3B, Germany) when walking along a 40 meter indoor track and on a treadmill. Both the TFA and CON walked on the two surfaces with five different speeds in random order. Walking speeds wer...

Research paper thumbnail of Hemodynamic responses to high intensity resistance training in patients with ischemic heart disease

Purpose Investigate the hemodynamic responses of resistance training (RT) with moderate load and ... more Purpose Investigate the hemodynamic responses of resistance training (RT) with moderate load and 15 repetitions versus RT with high load and 4 repetitions in patients with ischemic heart disease (IHD). Methods Fifteen medical stable males (n=11) and females (n=4) with IHD treated with PCI or coronary artery bypass graft surgery > six months ago (Table 1) were randomly allocated to test 1 and test 2 (Figure 1). All exercises were performed without breathing holding (Valsava maneuver). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were monitored before and continuously during each session. The hemodynamic status was assessed by impedance cardiography (PhysioFlow Enduro, Manatec, Folschviller, France)

Research paper thumbnail of Effecy of moderate and high intensity intermittent endurance exercise on post exercise hypotension

Research paper thumbnail of Skeletal muscle metabolism in poststroke patients during walking

Background: Is widely accepted that the central nervous system selects the preferred walking spee... more Background: Is widely accepted that the central nervous system selects the preferred walking speed (PWS) to minimize energy expenditure (EE). To conserve limited stores of carbohydrate (CHO) in the body, it is hypothesized that the PWS is most economical under conditions when CHO oxidation is restrained and fat oxidation is favored. Aim: To investigate the EE through measurements of the respiratory exchange ratio (RER) and rates of fat and CHO oxidation in relation to the total energy expenditure (TEE) during overground walking at the PWS. Method: The sample consisted of nineteen subacute stroke patients (mean age 72.6 ± 10.3 years ; body mass index (BMI) 26.1± 2.9; PWS 1.07±0.3 m/sec-1) and nine control subjects (mean age 71.2± 10.2 years; BMI 25.1±5.6; PWS 1.49±0.2 m/sec-1). Each subject walked for 7 minutes at their PWS around a 20 meter length rectangular room using a portable gas analyzer. Measurements of oxygen consumption and carbon dioxide production were recorded. Results: ...

Research paper thumbnail of The oxygen cost of walking is not a good measure for quantifying the physical effort of prosthetic ambulation

The oxygen cost of walking is not a good measure for quantifying the physical effort of prostheti... more The oxygen cost of walking is not a good measure for quantifying the physical effort of prosthetic ambulation Background The oxygen uptake (VO2) during walking is widely recognized as a measure of the whole body energy expenditure, while the oxygen cost of walking (Cw; ml kg

Research paper thumbnail of A review of the role of the partial pressure of carbon dioxide in mechanically loaded tissues: the canary in the cage singing in tune with the pressure ulcer mantra

Annals of biomedical engineering, 2015

Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distr... more Pressure ulcers (PUs) can occur in any situations where people are subjected to non-uniform distribution of pressure over a prolonged period. They can have devastating effects on the patients' well-being and in extreme conditions can prove fatal. In addition to traditional wisdom implicating mechanically induced ischaemia, there is strong evidence that other mechanisms play a role in the cascade of events which can initiate the PU damage process at the cellular level. Some of these refer to a metabolic imbalance with compromised delivery of nutrients and accumulation of waste products in the local environment of the cells. The approach of much research has focused on the measure of oxygen in compressed tissues as a means of predicting early damage. However, the present review adopting a hierarchical approach, using length scales ranging from cells through to human models, has revealed compelling evidence which highlights the importance of carbon dioxide levels and associated con...

Research paper thumbnail of Resistance exercise and acute blood pressure responses

The Journal of sports medicine and physical fitness, Jan 20, 2015

Compare the acute hemodynamic and cardiovascular responses of high load/low repetition resistance... more Compare the acute hemodynamic and cardiovascular responses of high load/low repetition resistance training (RT) to low load/high repetition RT. Thirteen healthy men performed four sets of 4 repetition maximum (RM) and 20RM leg--extensions without breath--holding. The RT was conducted in a randomized order and with 48 hours between bouts. Non--invasive beat--to--beat systolic and diastolic blood--pressure (SBP/DBP) was measured on the finger, while non--invasive cardiac output (CO) was assessed beat--to--beat by impedance--cardiography. Mean ± SD resting SBP/DBP and CO were 126 ± 14/73 ± 9 mmHg and 5.6 ± 9 L min --1 , respectively. Exercise SBP/DBP values increased to 154 ± 22/99 ±18 and 203 ± 33/126 ± 19 mmHg following 4RM and 20RM RT, respectively (compared to rest, all;; p < 0.001), and 20RM SBP/DBP values were higher than 4RM values (both, p < 0.001). The SBP increased from the first to the fourth set of exercise following the 20RM load (p < 0.01), but not so for the 4RM...

Research paper thumbnail of Energy expenditure of transfemoral amputees walking on a horizontal and tilted treadmill simulating different outdoor walking conditions

Prosthetics and Orthotics International, 2010

Background and aim: Transfemoral amputees often report that walking on tilted pavements or in ter... more Background and aim: Transfemoral amputees often report that walking on tilted pavements or in terrain with the prosthesis on the highest side is quite strenuous. This study investigates the energy expenditure of transfemoral amputees (n=8) walking on altered treadmill positions simulating different outdoor walking conditions. Method: Oxygen uptake at self selected speed of gait was measured during walking at three different treadmill positions: (I) Horizontal treadmill, (II) 3 % tilt in the sagittal plane and (III) 3 % tilt in both the sagittal and frontal plane of the treadmill.

Research paper thumbnail of Assessment of aerobic capacity and walking economy of unilateral transfemoral amputees

Prosthetics and Orthotics International, 2014

Studies of the maximal oxygen uptake (VO(2max)) of transfemoral amputees have mostly used protoco... more Studies of the maximal oxygen uptake (VO(2max)) of transfemoral amputees have mostly used protocols that activate a relatively small muscle mass. Consequently, transfemoral amputee VO(2max) may be systematically underestimated, and the validity of these test protocols is questionable. (1) Investigate validity and reliability of a VO(2max) walking protocol and (2) compare the VO(2max) of a transfemoral amputee group with a group of matching controls. (1) Randomized crossover study: walking versus running VO(2max) for the control group and (2) case-control study: transfemoral amputees versus control group VO(2max). Twelve transfemoral amputees and control participants performed a walking VO(2max) test with increasing treadmill inclinations to voluntary exhaustion. The control group also completed a running (&quot;gold-standard&quot;) VO(2max) test. Mean (standard deviation) control group VO(2max) following walking and running was similar, that is, 2.99 (0.6) L min(-1) and 3.09 (0.7) L min(-1), respectively. Mean (standard deviation) transfemoral amputee walking VO(2max) was 2.14 (0.8) L min(-1) (compared to CON; p &lt; 0.01). Mean intraclass correlation coefficient of repeated VO(2) measurements was 0.97, and within-subjects standard deviation was 60 mL min(-1). The walk protocol is valid. Walking VO(2max) of transfemoral amputees was 40% lower compared to control group. Reliability of the walking protocol is comparable to other walking protocols. Clinical relevance The design, alignment, and materials of prostheses are important for effective ambulation. Cardio-respiratory fitness is, however, also important in this regard, and a low fitness may compromise health and independent living. Hence, transfemoral amputees with low physical fitness should engage in regular physical activity to improve health, gait capacity, and independency.

Research paper thumbnail of Oxygen Uptake and Energy Expenditure during Treadmill Walking with Masai Barefoot Technology (MBT) Shoes

Journal of Physical Therapy Science, 2011

Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase ox... more Purpose] It is suggested that walking with Masai Barefoot Technology (MBT) shoes will increase oxygen uptake and result in greater consumption of energy relative to walking with conventional shoes, but this has not been sufficiently investigated. [Methods] To examine this supposition, ten subjects walked on a treadmill with different types of shoes (jogging or MBT shoes), treadmill inclinations (zero or 10 % inclination) and walking speeds (i.e. selfselected walking speed or fast walking speed). Oxygen uptake, heart rate, lung ventilation, ratings of perceived exertion and energy expenditure were measured during all walking conditions by a stationary metabolic cart.

Research paper thumbnail of Novel Design of an Optical Probe for Detecting Perfusion Changes in Buccal Tissue

IEEE Sensors Journal, 2000

Measuring the blood perfusion and microcirculation at a specific depth in human tissue is an impo... more Measuring the blood perfusion and microcirculation at a specific depth in human tissue is an important method to monitor oxygenation in critically ill patients. The optical probes, that are currently available in the market, are not capable of monitoring the blood perfusion from a given tissue layer and at a specific depth. We have designed a novel optical probe which is able to focus the light at a specific depth of ∼670 µm in buccal tissue. The new probe consists of two light guides for sending and detecting the reflected light from the sampling area (tissue), and a lens to focus the light into the desired depth of the tissue and collect it back from the same area. The new optical probe has been compared to a commercial laser Doppler probe by collecting data from the same sampling area. The result from our probe showed 15% higher accuracy in detecting changes in blood perfusion compared with an existing commercial probe.

Research paper thumbnail of Effect of concentric or eccentric weight training on the expression of heat shock proteins in m. biceps brachii of very well trained males

European Journal of Applied Physiology, 2006

Increased HSP expression in response to acute exercise is well documented in animal studies, and ... more Increased HSP expression in response to acute exercise is well documented in animal studies, and there is growing evidence that similar responses occur in man. In general, many human exercise studies have investigated the HSP response to low force continuous activity, while the knowledge about the HSP response to high force intermittent type of activity, like weight training, is so far sparse. In addition, most studies have used untrained subjects, and a common observation is that acute low force continuous activity in untrained individuals increases the HSP expression in these individuals.The main scope of this study was to investigate the HSP response in very well trained males subjected to longitudinal high intensity exercise, and if this response was dependent on exercise modality [i.e. eccentric (ECC) or concentric (CON) contractions]. Very well trained males performed progressive strength training consisting of either high force ECC or high force CON elbow flexions 2-3 times a week for 12 weeks. Compared with preexercise levels, HSP72 expression decreased by 46.1% (P<0.05) after CON contractions. GRP75 expression was unchanged after ECC or CON contractions, while ubiquitin expression decreased by 19.9% (P<0.02) after ECC contractions. These findings imply that chronic, intensive exercise may attenuate the HSP response in well-trained males.

Research paper thumbnail of Effect of training with different intensities and volumes on muscle fibre enzyme activity and cross sectional area in the m. triceps brachii

European Journal of Applied Physiology, 2008

This study primarily examined how intermittent versus continuous endurance training, using simila... more This study primarily examined how intermittent versus continuous endurance training, using similar or dissimilar volumes, aVected muscle Wbre enzyme activities in the triceps brachii muscle. Thirty-two subjects performed either intermittent (60% of 1RM) or continuous (30% of 1RM) elbow extensions 3 times week ¡1 in a training apparatus. Training was performed until either a low (Wve) or a high volume (8 weeks) was accumulated. Muscle biopsies from the m. triceps brachii were taken pre-and post training and following 8 weeks of detraining. Marker enzymes for muscle Wbre oxidative (succinate dehydrogenase SDH) and glycolytic (glycerophosphate dehydrogenase; -GPDH) capacity was assessed by histochemistry, and the resulting enzyme activities measured by image analysis. The type of training aVected enzyme activities diVerently. In type 1 Wbres, continuous and intermittent training was equally eVective in increasing SDH activity, while intermittent training increased SDH activity more than continuous training in type 2 Wbres (P < 0.05). Intermittent training increased -GPDH activity more than continuous training both in type 1 (P < 0.001) and type 2 Wbres (P < 0.05), but the increase in glycolytic capacity following intermittent training was larger in type 1 (54%) than in type 2 Wbres (23%). There was no eVect of training volume on oxidative or glycolytic capacity in either Wbre type. Thus, when training intensity is suYcient to stimulate to increases in oxidative and glycolytic capacity, the SDH and -GPDH response seems to be volume independent. Detraining reduced Post-T enzyme activities to baseline (all; P < 0.01).

Research paper thumbnail of Effect of training and detraining on the expression of heat shock proteins in m. triceps brachii of untrained males and females

European Journal of Applied Physiology, 2006

Forty untrained persons were randomized to four diVerent training protocols that exercised the m.... more Forty untrained persons were randomized to four diVerent training protocols that exercised the m. triceps brachii. Group 1 and 2 performed high intensity (HI) elbow extensions and group 3 and 4 performed low intensity (LI) elbow extensions. Group 1 and 3 trained until they had accumulated a matching high volume (HV) of training, while group 2 and 4 trained until they had accumulated a matching low volume (LV) of training. Training for 5-8 weeks increased the HSP72, HSP27 and GRP75 levels in the subjects' m. triceps brachii by 111, 71 and 192%, respectively ( . There were, however, no signiWcant diVerences in the heat shock protein (HSP) responses to training between the four training groups . The frequency of extreme responses to exercise was, however, higher after HI exercise than after LI exercise, indicating that HI exercise induces extreme HSP reactions in some subjects. When we assigned the subjects to three clusters, according to the total number of repetitions they had lifted, the subjects who had lifted the highest number of repetitions had lower PostExc HSP levels compared with subjects that lifted the low-est number of repetitions ( . Additionally, there was a negative non-linear regression between the subjects PreExc levels of HSP72, HSP27 and GRP75 and the percentage change in their respective protein concentration after training (r = ¡0.75, ¡0.89 and ¡0.88, all P < 0.0001). Thus, the PreExc level of HSPs seems to be an important "regulator" of HSP expression following the training.

Research paper thumbnail of Effect of training on the activity of five muscle enzymes studied on elite cross-country skiers

Acta Physiologica Scandinavica, 1999

This study examines the effect of training intensity on the activity of enzymes in m. vastus late... more This study examines the effect of training intensity on the activity of enzymes in m. vastus lateralis. Elite junior cross-country skiers of both sexes trained 12-15 h weeks-1 for 5 months at either moderate (60-70% of VO2max, MIG) or high training intensity (80-90% of the VO2max, close to the lactate threshold; HIG). Muscle biopsies for enzyme analyses and fibre typing were taken before and after the training period. Histochemical analyses on single fibres were done for three enzymes (succinate dehydrogenase [SDH], hydroxybutyrate dehydrogenase [HBDH], glycerol-3-phosphate dehydrogenase [GPDH]), while the activity of citrate synthase [CS] and phosphofructokinase [PFK] was measured on whole biopsies. The activity of GPDH was low in ST fibres and high in FT fibres. The activity of SDH and HBDH was high in both ST and FTa fibres but low in the FTb fibres. The HIG increased their performance more than the MIG did during the training period as judged from scores on a 20-min run test. The SDH activity rose by 6% for the HIG (P &lt; 0.02). No effects of training were found in the activities of CS, HBDH or GPDH, neither in the two training groups nor for the two genders (P &gt; or = 0.16). The PFK activity fell by 10% for the HIG (P=0.02), while no change was found for the MIG. For GPDH, CS and SDH the women&#39;s activity was approximately 20% less than the value for the men (P &lt; 0.03). For PFK and HBDH there was no sex difference (P &gt; or = 0.27). There were positive correlations between the activity of three of the enzymes (CS, SDH and GPDH) and the performance parameters (VO2max, cross-country skiing and running performance; r &gt; or = 0.6, P &lt; 0.01). No correlations were found between the PFK or HBDH activities and the performance parameters (r &lt; or = 0.16, P &gt; 0.05). This study suggests that intensities near the lactate threshold affect biochemical and physiological parameters examined in this study as well as the performance of elite skiers, and that the rate-limiting enzymes may be more sensitive to training than non-rate-limiting enzymes.

Research paper thumbnail of The physiological responses to repeated upper-body sprint exercise in highly trained athletes

European Journal of Applied Physiology, 2015

sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressi... more sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressively decreased (P < 0.05). m. triceps brachii and m. latissimus dorsi were highly desaturated already after the first sprint (all P < 0.05), whereas the response was delayed for m. biceps brachii and m. vastus lateralis. Correspondingly, increases in VO 2 mainly occurred over the first two sprints (P < 0.05) and plateaued at approximately 75 % of VO 2peak . 1RM correlated with power during the first four sprints and with average sprint power (r = 0.71-0.80, all P < 0.05), whereas VO 2peak correlated with power in the last three sprints (r = 0.60-0.71, all P < 0.05). Conclusions The main decrement in upper-body sprint performance was evident in the first five sprints, followed by highly desaturated muscles and a plateau in pulmonary oxygen uptake already after the first 2-3 sprints. While high maximal strength seems important for producing power, aerobic capacity correlates with power in the last sprints.