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Deakin University Introduction Low-load resistance exercise with blood-flow restriction (BFR) increases muscle strength and hypertrophy . However, for safety in ‘clinical’ use it is important to understand the cardiovascular responses to BFR exercise that have only been examined in comparison with similar light-load exercise without BFR and not high-load resistance exercise . Similarly, the cardiovascular responses to aerobic BFR exercise (walking, cycling) have not been compared with high-intensity aerobic exercise [3, 4]. Therefore, the aim of this study was to measure the cardiovascular stress of both resistance and aerobic BFR exercise compared with equal-intensity and high-intensity non-BFR exercise. Methods Participants (n=14) completed two exercise trials in a randomized crossover design. Each trial comprised 3
exercise bouts completed in order (light-intensity [LI]; LI+BFR; high-intensity [HI]). Each bout comprised 4 sets. Rest between sets was 1-min, and rest between bouts was 10 min. The exercise for one trial was a seated 45 degree inclined double-led press (LP) where intensity was 20% 1 RM for the LI and LI+BFR bouts (30, 15, 15 and 15 repetitions), and 80% 1 RM for the HI bout (8 repetitions per set). The other trial was treadmill exercise (TM) where intensity was 4 km/hr for the LI and LI+BFR bouts, and 80% VO2max for the HI bout. All TM sets were 2 min.
CO, SV and HR were measured prior to each bout, and during set 2 and 4. BP was measured immediately following set 2 and 4. Results Typical responses were observed for all variables (BP, HR, SV, CO) in all bouts over time (rest-to-exercise) in both TM and LP. For the TM LI+BFR bout sBP, HR, SV and CO were lower than HI but similar to LI. In LP, BP was generally similar between LI and HI bouts. However, for the LI+BFR bout, despite sBP being similar MAP and dBP were higher than in HI. CO was lower in the LI+BFR bout compared with HI but similar to LI, while HR was between LI and HI. SV in the LI+BFR bout was not different to LI or HI. Discussion These data show that the cardiovascular stress of BFR resistance exercise is more similar to traditional high-intensity resistance exercise while aerobic BFR exercise is more akin to light-intensity aerobic exercise. This suggests aerobic BFR exercise to be more suitable in ‘clinical’ populations than BFR resistance exercise to maintain/increase muscle mass and functional capacity. References 1. Wernbom M, et al. (2008). Scand J Med Sci Sport. 18(4), 401-16. 2. Takano H, et al. (2005). Eur J Appl Physiol. 95(1), 65-73. 3. Renzi CP, et al. (2010). Med Sci Sports Exerc. 42(4), 726-32.
4. Ozaki H, et al. (2010). J Sport Sci Med. 9(2), 224-30.
BRIEF CYCLING EXERCISE DOES NOT ALTER THE COMPLIANCE OF SUPERFICIAL AND DEEP VEINS IN RESTING UPPERARM Ooue, A., Kobayashi, Y., Sato, K., Yoneya, M., Sadamoto, T.
Japan Women's College of Physical Education Introduction Venous vessels have a large elasticity and compliance. Prolonged cycling exercise decreased venous compliance of forearm, which is caused by sympathetic venoconstriciton that indicates an elevation of venous vessel tone (Fortney et al. 1983). The increase in sympathetic nerve activity (SNA) during prolonged exercise is caused by both exercise-induced factors (central command and reflex neural control from exercising muscle) and the unloading of cardiopulmonary which is due to the decrease in central blood volume with the increase in sweating and skin blood flow. However, the increase in SNA related to only the former one does not alter venous compliance during static exercise. Thus, it is hypothesized that brief dynamic exercise, which causes the increase in SNA related to the exerciseinduced factors, does not change the venous compliance. To test our hypothesis, we assessed the venous compliance from pressure– cross sectional area (CSA) of vein curve during brief cycling exercise (Halliwill et al. 1999). In addition, we measured compliance of superficial and deep veins in resting upper arm, because the function and structure are different between both veins. Methods In 14 young subjects, the venous compliance was evaluated during resting (REST) and a 5-min cycling exercise at two loads with 35% (EX35) or 70% (EX70) of peak oxygen uptake. CSA in a superficial basilic vein and a deep brachial vein was measured by ultrasound technique during gradual deflation in the pressure (P) of cuff being inflated to 60 mmHg at 1 mmHg/s to provide a uniform pressure in the vein for the CSA measurement. The relation curve of CSA= β2×(P)2 + β1×(P) + β0 was determined in each vein and thereafter the venous compliance equation was obtained as the compliance = β1+ 2×β2×(P). Results Cuff pressure–superficial venous CSA curve shifted to downward according to exercise intensity. Cuff pressure–deep venous CSA curve during EX70% was also lower than that during REST. However, compliance of both superficial and deep vein did not differ among conditions. Discussion Cuff pressure–CSA curves of superficial and deep veins during exercise were lower than those during REST, indicating an elevation of venous vessel tone during exercise. However, compliance of both veins was not changed by the exercise. This result suggests that brief dynamic exercise, which causes the increase in SNA due to central command and reflex neural control from exercising muscle, induces the venoconstriction but it does not alter the venous compliance of both superficial and deep veins. References Fortney SM, Wenger CB, Bove JR, Nadel ER. (1983). J Appl Physiol, 55, 884−890. Halliwill JR, Minson CT, Joyner MJ. (1999) J Appl Physiol, 87, 1555-1563
BLOOD FLOW RESTRICTED LOW-LOAD RESISTANCE EXERCISE INDUCES TYPE 1 FIBRE SPECIFIC CHANGES IN HEAT
SHOCK PROTEINS AND GLYCOGEN CONTENT IN HUMAN SKELETAL MUSCLECumming, K.T., Wernbom, M., Paulsen, G., Raastad, T.
Norwegian School of Sport Sciences Introduction Heat shock proteins (HSP) have been identified as important chaperones for repair and stabilisation of stressed and damaged proteins (1). It appears that HSP70 expression increase after both damaging- and non-damaging muscle contractions, whereas the small HSP αB-crystallin seems to be more specifically responsive to muscle damaging exercise (2). Furthermore, submaximal isometric contractions have been shown to increase mostly HSP70 in type 1 fibres (3). In blood flow restricted resistance exercise performed with low loads the first part of the work is covered by mainly type 1 fibre recruitment. However, when each set is performed to failure, both fibre types will be recruited at some stage (4). It is therefore intriguing to study whether there are fibre type differences in the HSP response after blood flow restricted exercise. Methods Nine young healthy subjects performed unilateral knee-extensions at 30 % of 1RM.
One leg was exercised with partial blood flow restriction (BFRRE) induced by a pressure cuff (90-100 mm Hg), while the other leg was exercised with normal blood flow (free-flow). The exercise consisted of 5 sets to failure in the BFRRE leg (45 sec rest between sets) and the corresponding number of repetitions in the free-flow leg. Muscle biopsies were sampled from m. vastus lateralis at pre, 1h, 24h and 48h post exercise. Muscle biopsies were cut in 8 µm thick cross sections and stained against HSP70, αB-crystallin and myosin heavy chain 1.
Glycogen content was visualised with PAS-staining. Results Type 1 fibres showed significantly higher HSP70 and αB-crystallin staining intensity at baseline than type 2 fibres. Relative to pre exercise values, a significant increase in HSP70 staining intensity was seen in type 1 fibres at 24 and 48 hours post exercise in the BFRRE leg. These changes in staining intensity were significantly larger than in the free-flow leg. Fibres displaying high staining intensities against HSP70 showed low glycogen content, most prominent at 48 hours post exercise.
αB-crystallin staining intensity was not significantly altered in any leg compared to pre exercise values. Conclusion Immunohistochemical analysis demonstrated that BFRRE performed to fatigue induced an increase in HSP70 staining intensity in type 1 fibres at 24 and 48 hours post exercise, as previously shown after submaximal isometric contractions (3). Although strenuous low-load BFRRE recruits both fibre types (4), our study demonstrates that the type 1 fibres are more stressed during this type of exercise, probably because of more fatigue than in the type 2 fibres. Interestingly, glycogen content was very low in the stressed type 1 fibres 48 hours after exercise. Reference list 1)
Noble (2008). Appl Physiol Nutr Metab, 33: 1050-1065. 2) Morton (2008). Sports Med, 39: 643-662. 3) Tupling (2007). J Appl Physiol, 103:
2105-2111. 4) Krustrup (2009). Scand J Med Sci Sports, 19: 576-584.
TEMPORARY IMPACT OF BLOOD DONATION ON PHYSICAL PERFORMANCE AND HAEMATOLOGICAL PARAMETERS INWOMEN Stangerup, I.1, Kramp, N.L.1, Ziegler, A.K.1, Dela, F.1, Magnussen, K.2, Helge, J.W.2 University of Copenhagen Purpose: No former studies have examined how blood donation influences physical performance in women and weather being a female athlete is compatible with donating blood. The aim of this study was to clarify how VO2peak, time trial (TT) performance and haematological parameters are affected in women with normal iron stores (P-ferritin40µg/L) and women with low iron stores (P-ferritin 12µg/L) following a standard 450ml blood donation and when they can expect to be back to their physical performance level again.
Methods: VO2peak measured by an incremental cycle ergometer test, performance in a 3km treadmill TT and blood parameters were measured at baseline, 3, 7, 14, 21 and 28 days after blood donation in 14 women with normal iron stores and 6 women with low iron stores. Anthropometrics were measured at baseline and day 28. Results: Mean age was 34.1 ±2.2. Mean body weight was 62.0 ±1.2.
There was no difference between the two groups in anthropometrics at baseline or at day 28. Body fat decreased 3.2% otherwise anthropometrics did not change in the study period. VO2peak was reduced by 6.9% from 2951 ±79 at baseline to 2758 ±71 mL/min 3 days after blood donation and remained below baseline through the study period (P0.001). TT performance was attenuated by 5.6% from baseline (868 ±28s) to (917 ±26s) at day 3. Blood haemoglobin (B-Hgb) declined (P0.001) 6.4% from 8.4 ±0.1 to 7.9 ±0.1mmol/L from baseline to day 3, respectively. Both TT and B-Hgb were recovered 14 days after blood donation (P0.001). There was no difference in VO2peak, TT and B-Hgb between the two groups at baseline or in response to blood donation. Plasma ferritin (P-ferritin) at baseline was 66 ±7 in the women with normal iron stores and 28±3µg/L in the women with low iron stores. P-ferritin dropped to a nadir of 65% 28 days after blood donation in the group with normal iron stores, whereas P-ferritin in the group with low iron stores remained unchanged in response to blood donation. Conclusion: VO2peak was not fully recovered 28 days after a blood donation despite of the normalization of B-Hgb and TT performance 14 days after blood donation. Since iron plays a key role in muscle mitochondrial enzymes and respiratory proteins, low iron availability might explain the observed dissociation between recovery in B-Hgb and VO2peak. Female athletes should expect more than 28 days to recover from blood donation before entering competition. Female athletes being blood donors should be advised to take iron supplementation to prevent iron depletion, deficiency or anemia and to secure optimal physical performance.