Category Archives: Physiology

Studies showing the physiology of Galileo on the body.

Cellular and Humoral Immunological Parameters.

Cell Mol Immunol, 2015; 12(4): 483-92, PMID: 25382740 external link

Effects of 60-day bed rest with and without exercise on cellular and humoral immunological parameters.

Hoff P, Belavy DL, Huscher D, Lang A, Hahne M, Kuhlmey AK, Maschmeyer P, Armbrecht G, Fitzner R, Perschel FH, Gaber T, Burmester GR, Straub RH, Felsenberg D, Buttgereit F
1] Charite Universitatsmedizin Berlin, Department of Rheumatology and Clinical Immunology, Berlin, Germany [2] Deutsches Rheuma-Forschungszentrum (DRFZ), Berlin, Germany [3] Berlin-Brandenburg Center of Regenerative Therapies (BCRT), Berlin, Germany.

Abstract

Purpose: Exercise at regular intervals is assumed to have a positive effect on immune functions. Conversely, after spaceflight and under simulated weightlessness (e.g., bed rest), immune functions can be suppressed. We aimed to assess the effects of simulated weightlessness (Second Berlin BedRest Study; BBR2-2) on immunological parameters and to investigate the effect of exercise (resistive exercise with and without vibration) on these changes.

Method: Twenty-four physically and mentally healthy male volunteers (20-45 years) performed resistive vibration exercise (n=7), resistance exercise without vibration (n=8) or no exercise (n=9) within 60 days of bed rest. Blood samples were taken 2 days before bed rest, on days 19 and 60 of bed rest. Composition of immune cells was analyzed by flow cytometry. Cytokines and neuroendocrine parameters were analyzed by Luminex technology and ELISA/RIA in plasma.

General changes over time were identified by paired t-test, and exercise-dependent effects by pairwise repeated measurements (analysis of variance (ANOVA)). With all subjects pooled, the number of granulocytes, natural killer T cells, hematopoietic stem cells and CD45RA and CD25 co-expressing T cells increased and the number of monocytes decreased significantly during the study; the concentration of eotaxin decreased significantly. Different impacts of exercise were seen for lymphocytes, B cells, especially the IgD(+) subpopulation of B cells and the concentrations of IP-10, RANTES and DHEA-S.

Results: We conclude that prolonged bed rest significantly impacts immune cell populations and cytokine concentrations. Exercise was able to specifically influence different immunological parameters.

Conclusion: In summary, our data fit the hypothesis of immunoprotection by exercise and may point toward even superior effects by resistive vibration exercise.

Muscle Histology Changes

Acta Myol, 2016; 34(2-3): 133-8, PMID: 27199541 external link

Muscle histology changes after short term vibration training in healthy controls

Schoser B
Friedrich-Baur-Institute, Department of Neurology, Klinikum der Universitat Munchen, Germany.

Abstract

Purpose: In search for additional counter measures of muscle atrophy vibration exercise training may have substantial effort for patients with neuromuscular disorders. To cover safety aspects and obtain muscle morphology data, a pilot study was performed in eleven healthy men.

Method: Countermovement jump, squat jump, drop jump and one repetition maximum test (1RM) were performed on a force platform before and after a 6 week training period. No severe side effects were found.

Results: Repeated needle muscle biopsies of the vastus lateralis muscle revealed a selective pre- to post-training type-2 myofiber hypertrophy of up to 50 %. The hypertrophy factors were 160 and 310, for type-2 myofibers. The mechanography system showed a significant increase in the 1RM maximum weight lifted (pre: 111,8 kg +/- 11,5; post: 140,9 kg +/- 13,00; p < 0,001).

Conclusion: Vibration exercise is a safe and effective technique which desires further approval as counter measure in different types of neuromuscular atrophy.

Stretch Reflexes

Eur J Appl Physiol (2010) 110:143–151 DOI 10.1007/s00421-010-1483-x  Accepted: 9 April 2010 / Published online: 24 April 2010 _ Springer-Verlag 2010

EMG activity during whole body vibration: motion artifacts or stretch reflexes?

Ramona Ritzmann • Andreas Kramer • Markus Gruber • Albert Gollhofer • Wolfgang Taube

Abstract

Purpose: The validity of electromyographic (EMG) data recorded during whole body vibration (WBV) is controversial. Some authors ascribed a major part of the EMG signal to vibration-induced motion artifacts while others have interpreted the EMG signals as muscular activity caused at least partly by stretch reflexes. The aim of this study was to explore the origin of the EMG signal during WBV using several independent approaches.

Method: In ten participants, the latencies and spectrograms of stretch reflex responses evoked by passive dorsiflexions in an ankle ergometer were compared to those of the EMG activity of four leg muscles during WBV. Pressure application to the muscles was used to selectively reduce the stretch reflex, thus permitting to distinguish stretch reflexes from other signals. To monitor motion artifacts, dummy electrodes were placed close to the normal electrodes.

Results: Strong evidence for stretch reflexes was found: the latencies of the stretch reflex responses evoked by dorsiflexions were almost identical to the supposed stretch reflex responses during vibration (differences of less than 1 ms). Pressure application significantly reduced the amplitude of both the supposed stretch reflexes during vibration (by 61 ± 17%, p\0.001) and the stretch reflexes in the ankle ergometer (by 56 ± 13%, p\0.01). The dummy electrodes showed almost no activity during WBV (7 ± 4% of the corresponding muscle’s iEMG signal). The frequency analyses revealed no evidence of motion artifacts.

Conclusion: The present results support the hypothesis of WBV-induced stretch reflexes. Contribution of motion artifacts to the overall EMG activity seems to be insignificant.

Keywords: Electromyography _ Afferent _Pressure application _ Frequency analysis _ Spectrogram _Latency

H-Reflex, Stretch Reflex & Short-Latency

Scand J Med Sci Sports, 2011

The effect of whole body vibration on the H-reflex, the stretch reflex, and the short-latency response during hopping.

Ritzmann R, Kramer A, Gollhofer A, Taube W
Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany.

Abstract

The effect of whole body vibration (WBV) on reflex responses is controversially discussed in the literature.

PURPOSE:  In this study, three different modalities of reflex activation with increased motor complexity have been selected to clarify the effects of acute WBV on reflex activation: 1) the electrically evoked H-reflex, 2) the mechanically elicited stretch reflex, and 3) the short-latency response (SLR) during hopping.

METHOD:  WBV-induced changes of the H-reflex, the stretch reflex, and the SLR during hopping were recorded in the soleus and gastrocnemius muscles and were analyzed before, during (only the H-reflex), immediately after, 5 min and 10 min after WBV.

RESULTS:  The main findings were that: 1)  the H-reflexes were significantly reduced during and at least up to 5 min after WBV, 2) the stretch reflex amplitudes were also significantly reduced immediately after WBV but recovered to their initial amplitudes within 5 min, and 3) the SLR during hopping showed no vibration-induced modulation.  With regard to the modalities with low motor complexities, the decreased H- and stretch reflex responses are assumed to point toward a reduced Ia afferent transmission during and after WBV. However, it is assumed that during hopping, the suppression of reflex sensitivity is compensated by facilitatory mechanisms in this complex motor task.

PMID: 22011018

Acute Effects of WBV on Soleus H-Reflex

International Journal of Physiotherapy and Rehabilitation, October 2010, Vol. 1, Issue 1, 30-40

Acute Effects of Whole Body Vibration on Rate of Force Development and Electromechanical Delay.

Junggi Hong Assistant Professor, Department of Exercise Science, Willamette University.  K. Kipp, Dept of PM&R University of Michigan. S.T. Johnson & M.A. Hoffman University of Oregon State

ABSTRACT

Background: The ability to generate rapid and powerful muscle contractions within a short period of time is an important factor for both enhancing sports performance and preventing injuries. Recently, whole-body vibration (WBV) has been introduced as a novel training method designed to produce neuromuscular improvement similar to that of power and strength training. However, to date there are only limited data on the acute effects of WBV on the neuromuscular system. Furthermore, there is little understanding about the responsiveness of the neuromuscular system to acute exposure WBV.

Research question: The present study examined the effect of acute WBV training on the rate of force development (RFD) and electromechanical delay (EMD) in the soleus muscle.

Type of study: Randomized controlled study.

Methods: Forty young individuals with no leg injuries were randomly assigned to an experimental or control group. The experimental group received acute WBV (3 bouts of 2 minutes). The control group adopted the same position (squat position) on the vibration platform for an equal time but received no vibration.

Results: The experimental (WBV) group demonstrated a significant group °— time interaction for the rate of force development (RFD) and electromechanical delay (EMD) representing 15.6% (from 274Nm/sec to 323 Nm/sec) and 16% (from 23.42 ms to 19.3 ms) improvement.

Conclusions: It appears that acute WBV enhances RFD and EMD of the soleus musclin young healthy subjects.

KEY WORDS: Whole body vibration, Neurological adaptation, Rate of force development, Electromechanical delay, EMG

Exhaustive Vibration Elicits Mild Cardiovascular Exertion

Clin Physiol. 2000 Mar;20(2):134-42.

Acute physiological effects of exhaustive whole-body vibration exercise in man.

Rittweger J1, Beller G, Felsenberg D.

Abstract

Objective: Vibration exercise (VE) is a new neuromuscular training method which is applied in athletes as well as in prevention and therapy of osteoporosis.

Method: The present study explored the physiological mechanisms of fatigue by VE in 37 young healthy subjects. Exercise and cardiovascular data were compared to progressive bicycle ergometry until exhaustion. VE was performed in two sessions, with a 26 Hz vibration on a ground plate, in combination with squatting plus additional load (40% of body weight).

Results: After VE, subjectively perceived exertion on Borg’s scale was 18, and thus as high as after bicycle ergometry. Heart rate after VE increased to 128 min-1, blood pressure to 132/52 mmHg, and lactate to 3.5 mM. Oxygen uptake in VE was 48.8% of VO2max in bicycle ergometry. After VE, voluntary force in knee extension was reduced by 9.2%, jump height by 9.1%, and the decrease of EMG median frequency during maximal voluntary contraction was attenuated. The reproducibility in the two VE sessions was quite good: for heart rate, oxygen uptake and reduction in jump height, correlation coefficients of values from session 1 and from session 2 were between 0.67 and 0.7. Thus, VE can be well controlled in terms of these parameters. Surprisingly, an itching erythema was found in about half of the individuals, and an increase in cutaneous blood flow.

Conclusion: It follows that exhaustive whole-body VE elicits a mild cardiovascular exertion, and that neural as well as muscular mechanisms of fatigue may play a role.

PMID: 10735981

Increased Skeletal Muscle and Performance

Int J Sports Med. 2011 Oct;32(10):781-7. doi: 10.1055/s-0031-1277215. Epub 2011 Aug 25.

Combined effects of whole-body vibration, resistance exercise, and vascular occlusion on skeletal muscle and performance.

Item F1, Denkinger J, Fontana P, Weber M, Boutellier U, Toigo M.

Abstract

Objective: The purpose of this study was to evaluate the effects of a new high-intensity training modality comprised of vibration exercise with superimposed resistance exercise and vascular occlusion (vibroX) on skeletal muscle and performance.

Method: Young untrained women were randomized to either train in a progressive mode on 3 days per week for 5 weeks ( N=12) or to maintain a sedentary lifestyle ( N=9).

Results: VibroX increased peak cycling power (+9%, P=0.001), endurance capacity (+57%, P=0.002), ventilatory threshold (+12%, P<0.001), and end-test torque (+15%, P=0.002) relative to the sedentary group. Training load increased by 84.5% ( P<0.001) after vibroX. The increases were paralleled by increases in myosin heavy chain type 1 vastus lateralis muscle fiber cross-sectional area (+14%, P=0.031) and proportion (+17%, P=0.015), thigh lean mass (+4%, P=0.001), capillary-to-fiber ratio (+14%, P=0.003), and cytochrome c oxidase activity. Conversely, maximal values for oxygen consumption, cardiac output, isokinetic leg extension power and jumping power remained unaffected. Notably, vastus lateralis muscle adaptations were achieved with a very low weekly training volume.

Conclusion: We conclude that vibroX quickly increases muscle (fiber) size, capillarization, and oxidative potential, and markedly augments endurance capacity in young women.

© Georg Thieme Verlag KG Stuttgart · New York.

PMID: 21870317

 

Influence of WBV on Metabolic Power

Int J Sports Med. 2002 Aug;23(6):428-32.

Oxygen uptake in whole-body vibration exercise: influence of vibration frequency, amplitude, and external load.

Rittweger J1, Ehrig J, Just K, Mutschelknauss M, Kirsch KA, Felsenberg D.

Abstract

Objective: Vibration exercise (VbX) is a new type of physical training to increase muscle power. The present study was designed to assess the influence of whole-body VbX on metabolic power.

Method: Specific oxygen uptake (sVO(2)) was assessed, testing the hypotheses that sVO(2) increases with the frequency of vibration (tested in 10 males) and with the amplitude (tested in 8 males), and that the VbX-related increase in sVO(2) is enhanced by increased muscle force (tested in 8 males). With a vibration amplitude of 5 mm, a linear increase in sVO(2) was found from frequencies 18 to 34 Hz (p < 0.01).

Results: Each vibration cycle evoked an oxygen consumption of approximately 2.5 micro l x kg(-1). At a vibration frequency of 26 Hz, sVO(2) increased more than proportionally with amplitudes from 2.5 to 7.5 mm. With an additional load of 40 % of the lean body mass attached to the waist, sVO(2) likewise increased significantly. A further increase was observed when the load was applied to the shoulders.

Conclusion: The present findings indicate that metabolic power in whole-body VbX can be parametrically controlled by frequency and amplitude, and by application of additional loads. These results further substantiate the view that VbX enhances muscular metabolic power, and thus muscle activity.

PMID: 12215962 [PubMed – indexed for MEDLINE]

WBV Increases Skin Blood Flow

Med Sci Monit. 2007 Feb;13(2):CR71-6.

The effect of whole body vibration on lower extremity skin blood flow in normal subjects.

Lohman EB 3rd1, Petrofsky JS, Maloney-Hinds C, Betts-Schwab H, Thorpe D.

Abstract

BACKGROUND:

Circulation plays a vital role in tissue healing. Increases in muscle flexibility and strength, secretion of hormones important in the regeneration and repair process, blood flow, and strength of bone tissues has been attributed to whole body vibration (WBV) combined with exercise. The purpose of the study was to determine the effects of short-duration, high-intensity, isometric weight bearing exercise (vibration exercise [VE]) and vibration only on skin blood flow (SBF).

MATERIAL/METHODS:

Forty-five subjects 18-43 years of age were randomly divided into three groups: Group 1 – VE, Group 2 – exercise only, and Group 3 – vibration only. SBF was measured using a laser Doppler imager at three time intervals: 1) initial base line, 2) immediately following intervention, and 3) 10-minutes following intervention.

RESULTS:

There was no significant difference between the three groups’ SBF prior to intervention. Immediately following the intervention a difference among groups was found. Post hoc testing revealed that Group 3 subjects‘ mean SBF was significantly increased at both post-intervention time intervals.

CONCLUSION:

The study findings suggest that short duration vibration alone significantly increases SBF; doubling mean SBF for a minimum of 10 minutes following intervention. The emerging therapeutic modality of WBV as a passive intervention appears to increase SBF in individuals with healthy microcirculation.

PMID: 17261985

Rapid Rise in Muscle Force

International Journal of Physiotherapy and Rehabilitation, October 2010, Vol. 1, Issue 1, 30-40 / J. Hong, K. Kipp, S.T. Johnson, M.A.Hoffman / ˝2010, International Journal of Physiotherapy and Rehabilitation

Effects of 4 weeks whole body vibration on electromechanical delay, rate of force development, and presynaptic inhibition.

1) Department of Exercise Science, Willamette University, 900 State Street, Salem, OR 9730; 2) Department of Physical Medicine and Rehabilitation University of Michigan, 325 E. Eisenhower Ste. 100 Ann Arbor, MI 48109; 3) Department Nutrition and Exercise Science, Oregon State University 3, Corvallis OR 97331 / Email: jhong@willamette.edu

Abstract

Objective: Long-term functional changes after whole-body vibration (WBV) training have been attributed to adaptations in the neuromuscular system. The present study examined the effect of four weeks of WBV training on muscle function outcome variables [(rate of force development (RFD), electromechanical delay (EMD)], and spinal control mechanisms (pre-synaptic inhibition).

Method: Forty young individuals with no history of lower leg injuries were randomly assigned to an experimental or control group. The experimental group received WBV training (three bouts of two minutes, three times a week) for four weeks. During each of the training sessions, the subjects stood on the vibration platform with the knees slightly flexed. The control group performed periods of standing in the same position as the experimental subjects.

Results: After four weeks of WBV training, the experimental (WBV) group demonstrated a significant improvement in electromechanical delay (EMD). The results also showed a significant group Å~ test interaction for RFD and intrinsic pre-synaptic inhibition (IPI) over the course of the study.

Conclusion: Enhanced neuromuscular activation (EMD and RFD) and increased spinal reflex gain followed by 4 weeks of WBV training indicate that WBV training might be used not only for athletes engaged in sports that require explosive type of muscular activation, but also for the elderly individual who need to exert a rapid rise in muscle force in injury related situations.

Keywords: whole body vibration, neurological adaptation, rate of force development, electromechanical delay, pre-synaptic inhibition, H-reflex

EMG Muscle Activity During WBV

©Journal of Sports Science and Medicine (2013) 12, 439-446

Variations in Neuromuscular Activity of Thigh Muscles during Whole-Body Vibration in Consideration of Different Biomechanical Variables

Dennis Perchthaler 1, Thomas Horstmann 2,3 and Stefan Grau 1
1 Department of Sports Medicine, Medical Clinic, University of Tuebingen, Germany
2 Faculty for Sport and Health Sciences, Technische Universität München, Munich, Germany
3 Medical Park Bad Wiessee St. Hubertus, Bad Wiessee, Germany

Abstract

Purpose: The intention of this study was to systematically analyze the impact of biomechanical variables in terms of different vibration frequencies, amplitudes and knee angles on quadriceps femoris and hamstring activity during exposure to whole-body vibration (WBV).

Methods: 51 healthy men and women (age 55 ± 8 years) voluntary participated in the study and were randomly allocated to five different vibration-frequency groups. Each subject performed 9 static squat positions (3 amplitudes x 3 knee angles) on a side alternating vibration platform.

Surface electromyography (EMG) was used to record the neuromuscular activity of the quadriceps femoris and hamstring muscles. Maximal voluntary contractions (MVCs) were performed prior to the measurements to normalize the EMG signals. A three-way mixed ANOVA was performed to analyze the different effects of the biomechanical variables on muscle activity.

Results: Depending on the biomechanical variables, EMG muscle activity ranged between 18.2 and 74.1% MVC in the quadriceps femoris and between 5.2 and 27.3% MVC in the hamstrings during WBV. The highest levels of muscle activation were found at high frequencies and large amplitudes. Especially in the quadriceps femoris muscle, a WBV frequency of 30 Hz led to a significant increase in muscle activity compared to the other tested frequencies. However, it seems that knee angle is only relevant for the quadriceps femoris muscle.

Conclusion: The results of this study should give more information for developing individual training protocols for WBV treatment in different practical applications.
Key words: Vibration training, surface electromy