Female pheromones modulate flight muscle activation patterns during preflight warm-up

At low ambient temperature Helicoverpa zea male moths engage in warm-up behavior prior to taking flight in response to an attractive female pheromone blend. Male H. zea warm up at a faster rate when sensing the attractive pheromone blend compared with unattractive blends or blank controls ( Crespo et al. 2012 ), but the mechanisms involved in this olfactory modulation of the heating rate during preflight warm-up are unknown. Here, we test three possible mechanisms for increasing heat production: 1) increased rate of muscle contraction; 2) reduction in mechanical movement by increased overlap in activation of the antagonistic flight muscles; and 3) increased activation of motor units. To test which mechanisms play a role, we simultaneously recorded electrical activation patterns of the main flight muscles (dorsolongitudinal and dorsoventral muscles), wing movement, and thoracic temperature in moths exposed to both the attractive pheromone blend and a blank control. Results indicate that the main mechanism responsible for the observed increase in thoracic heating rate with pheromone stimulation is the differential activation of motor units during each muscle contraction cycle in both antagonistic flight muscles. This additional activation lengthens the contracted state within each cycle and thus accounts for the greater heat production. Interestingly, the rate of activation (frequency of contraction cycles) of motor units, which is temperature dependent, did not vary between treatments. This result suggests that the activation rate is determined by a temperature-dependent oscillator, which is not affected by the olfactory stimulus, but activation of motor units is modulated during each cycle.

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Activation of the Fibrillar Muscles in the Bumblebee During Warm-Up, Stabilization of Thoracic Temperature and Flight

Journal of Experimental Biology ◽

10.1242/jeb.58.3.677 ◽

1973 ◽

Vol 58 (3) ◽

pp. 677-688

Author(s):

BERND HEINRICH ◽

ANN E. KAMMER

Keyword(s):

Heat Production ◽

Action Potentials ◽

Spike Frequency ◽

Warm Up ◽

Ambient Temperatures ◽

Heating And Cooling ◽

Thoracic Temperature ◽

Flight Muscles ◽

Frequency Of Action Potentials ◽

Physical Laws

1. Extracellular action potentials and thoracic temperatures (TTh) were simultaneously recorded from the fibrillar flight muscles of Bombus vosnesenskii queens during preflight warm-up, during stabilization of TTh in stationary bees, and during fixed flight. 2. In most stationary bees during warm-up and during the stabilization of TTh the rate of heat production, as calculated from thoracic temperature and passive rates of cooling, is directly related to the frequency of action potentials in the muscles. 3. The rate of heat production increases throughout warm-up primarily because of a greater spike frequency at higher TTh. 4. In stationary bees during the stabilization of TTh at different ambient temperatures (TA) the fibrillar muscles are activated by any in a continuous range of spike frequencies, rather than only by on-off responses. 5. Regulation of TTh in stationary bees may involve not only changes in the rate of heat production but also variations of heat transfer from the thorax to the abdomen. 6. During fixed flight the fibrillar muscles are usually activated at greater rates at the initiation of flight than later in flight, but the spike frequency and thus heat production are not varied in response to differences in TA and heating and cooling rates. 7. During fixed flight TTh is not regulated at specific set-points; TTh appears to vary passively in accordance with the physical laws of heating and cooling. 8. Differences in the TTh of bees in free and in fixed flight are discussed with regard to mechanisms of thermoregulation.

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A peripheral governor regulates muscle contraction

Applied Physiology Nutrition and Metabolism ◽

10.1139/h10-073 ◽

2011 ◽

Vol 36 (1) ◽

pp. 1-11 ◽

Cited By ~ 23

Author(s):

Brian R. MacIntosh ◽

M. Reza S. Shahi

Keyword(s):

Muscle Contraction ◽

Muscle Activation ◽

Human Subjects ◽

Ryanodine Receptors ◽

Motor Units ◽

Voluntary Exercise ◽

Whole Body ◽

Peripheral Fatigue ◽

Metabolic Demand ◽

Membrane Excitability

Active skeletal muscles are capable of keeping the global [adenosine triphosphate (ATP)] reasonably constant during exercise, whether it is mild exercise, activating a few motor units, or all-out exercise using a substantial mass of muscle. This could only be accomplished if there were regulatory processes in place not only to replenish ATP as quickly as possible, but also to modulate the rate of ATP use when that rate threatens to exceed the rate of ATP replenishment, a situation that could lead to metabolic catastrophe. This paper proposes that there is a regulatory process or “peripheral governor” that can modulate activation of muscle to avoid metabolic catastrophe. A peripheral governor, working at the cellular level, should be able to reduce the cellular rate of ATP hydrolysis associated with muscle contraction by attenuating activation. This would necessarily cause something we call peripheral fatigue (i.e., reduced contractile response to a given stimulation). There is no doubt that peripheral fatigue occurs. It has been demonstrated in isolated muscles, in muscles in situ with no central nervous system input, and in intact human subjects performing voluntary exercise with small muscle groups or doing whole-body exercise. The regulation of muscle activation is achieved in at least 3 ways (decreasing membrane excitability, inhibiting Ca2+release through ryanodine receptors, and decreasing the availability of Ca2+in the sarcoplasmic reticulum), making this a highly redundant control system. The peripheral governor attenuates cellular activation to reduce the metabolic demand, thereby preserving ATP and the integrity of the cell.

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Altered muscle activation patterns in symptomatic women during pelvic floor muscle contraction and Valsalva manouevre

Neurourology and Urodynamics ◽

10.1002/nau.20183 ◽

2006 ◽

Vol 25 (3) ◽

pp. 268-276 ◽

Cited By ~ 65

Author(s):

Judith A. Thompson ◽

Peter B. O'Sullivan ◽

N. Kathryn Briffa ◽

Patricia Neumann

Keyword(s):

Pelvic Floor ◽

Muscle Contraction ◽

Muscle Activation ◽

Pelvic Floor Muscle ◽

Activation Patterns ◽

Pelvic Floor Muscle Contraction ◽

Muscle Activation Patterns

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Differences in muscle activation patterns during pelvic floor muscle contraction and Valsalva manouevre

Neurourology and Urodynamics ◽

10.1002/nau.20203 ◽

2006 ◽

Vol 25 (2) ◽

pp. 148-155 ◽

Cited By ~ 51

Author(s):

Judith A. Thompson ◽

Peter B. O'Sullivan ◽

N. Kathryn Briffa ◽

Patricia Neumann

Keyword(s):

Pelvic Floor ◽

Muscle Contraction ◽

Muscle Activation ◽

Pelvic Floor Muscle ◽

Activation Patterns ◽

Pelvic Floor Muscle Contraction ◽

Muscle Activation Patterns

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Acute Effect of Kettlebell Swings on Sprint Performance

Sports ◽

10.3390/sports7020036 ◽

2019 ◽

Vol 7 (2) ◽

pp. 36 ◽

Cited By ~ 1

Author(s):

Kishen Kartages ◽

Guy Wilson ◽

Che Fornusek ◽

Mark Halaki ◽

Daniel Hackett

Keyword(s):

Muscle Activation ◽

Random Order ◽

Acute Effect ◽

Sprint Performance ◽

Activation Patterns ◽

Warm Up ◽

Sprint Time ◽

Muscle Activation Patterns ◽

Time Interaction ◽

Condition Effect

Previous research has shown that kettlebell swings (KBS), utilizing the hip-hinge technique, exhibit similar lower-limb muscle activation patterns to sprint running. This study investigated whether the inclusion of KBS in the warm-up enhances sprint performance. Moderately trained males (n = 12) and females (n = 8) performed KBS and a control (CON) condition (passive rest) in random order before performing three 20-m sprint trials separated by 4 min. No condition (KBS versus CON) effects, time effects or condition by time interactions were found for sprint times at 5-m and 10-m. A significant time effect was found for sprint time at 20-m with faster sprint time at 12 min compared to 4 min (p = 0.022). No condition effect or condition by time interaction was found for sprint time at 20-m. Small to moderate correlations were found for change in sprint time (CON minus KBS) and KBS load at 4, 8, and 12 min. It appears the KBS is not effective for potentiating 20-m sprint performance; however, any potential benefit from the inclusion of KBS as a preconditioning exercise for sprinting may be influenced by individual strength capabilities with KBS.

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Keep calm and hang on: EMG activation in the forelimb musculature of three-toed sloths (Bradypus variegatus)

Journal of Experimental Biology ◽

10.1242/jeb.218370 ◽

2020 ◽

Vol 223 (14) ◽

pp. jeb218370 ◽

Cited By ~ 2

Author(s):

Marissa A. Gorvet ◽

James M. Wakeling ◽

Dakota M. Morgan ◽

Daniel Hidalgo Segura ◽

Judy Avey-Arroyo ◽

...

Keyword(s):

Muscle Activation ◽

Force Production ◽

Motor Units ◽

The Body ◽

Elbow Flexors ◽

Opposite Pattern ◽

Activation Patterns ◽

Fine Wire ◽

Bradypus Variegatus ◽

The Cost

ABSTRACTSloths exhibit below branch locomotion whereby their limbs are loaded in tension to support the body weight. Suspensory behaviors require both strength and fatigue resistance from the limb flexors; however, skeletal muscle mass of sloths is reduced compared with other arboreal mammals. Although suspensory locomotion demands that muscles are active to counteract the pull of gravity, it is possible that sloths minimize muscle activation and/or selectively recruit slow motor units to maintain support, thus indicating neuromuscular specializations to conserve energy. Electromyography (EMG) was evaluated in a sample of three-toed sloths (Bradypus variegatus; N=6) to test this hypothesis. EMG was recorded at 2000 Hz via fine-wire electrodes implanted into two suites of four muscles in the left forelimb while sloths performed suspensory hanging (SH), suspensory walking (SW) and vertical climbing (VC). All muscles were minimally active for SH. During SW and VC, sloths moved slowly (duty factor: 0.83) and activation patterns were consistent between behaviors; the flexors were activated early and for a large percentage of limb contact, whereas the extensors were activated for shorter burst durations on average and showed biphasic (contact and swing) activity. Muscle activities were maximal for the elbow flexors and lowest for the carpal/digital flexors, and overall activity was significantly greater for SW and VC compared with SH. Wavelet analysis indicated high mean EMG frequencies from the myoelectric intensity spectra coupled with low burst intensities for SH, although the opposite pattern occurred for SW and VC, with the shoulder flexors and elbow flexor, m. brachioradialis, having extremely low mean EMG frequencies that are consistent with recruitment of slow fibers. Collectively, these findings support the hypothesis and suggest that sloths may selectively recruit smaller, fast motor units for suspensory postures but have the ability to offset the cost of force production by recruitment of large, slow motor units during locomotion.

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Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18031366 ◽

2021 ◽

Vol 18 (3) ◽

pp. 1366

Author(s):

Roland van den Tillaar ◽

Eirik Lindset Kristiansen ◽

Stian Larsen

Keyword(s):

Muscle Activity ◽

Muscle Activation ◽

Gluteus Maximus ◽

Knee Extensors ◽

Force Output ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Prime Movers ◽

Almost All ◽

Height Data

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

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Electromyographic activation patterns during swallowing in older adults

Scientific Reports ◽

10.1038/s41598-021-84972-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jin Young Ko ◽

Hayoung Kim ◽

Joonyoung Jang ◽

Jun Chang Lee ◽

Ju Seok Ryu

Keyword(s):

Older Adults ◽

Viscous Fluid ◽

Muscle Activation ◽

Fatty Infiltration ◽

Liquid Volume ◽

Type I ◽

Type Ii ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Age Related

AbstractAge-related weakness due to atrophy and fatty infiltration in oropharyngeal muscles may be related to dysphagia in older adults. However, little is known about changes in the oropharyngeal muscle activation pattern in older adults. This was a prospective and experimental study. Forty healthy participants (20 older [> 60 years] and 20 young [< 60 years] adults) were enrolled. Six channel surface electrodes were placed over the bilateral suprahyoid (SH), bilateral retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles. Electromyography signals were then recorded twice for each patient during swallowing of 2 cc of water, 5 cc of water, and 5 cc of a highly viscous fluid. Latency, duration, and peak amplitude were measured. The activation patterns were the same, in the order of SH, TH, and StH, in both groups. The muscle activation patterns were classified as type I and II; the type I pattern was characterized by a monophasic shape, and the type II comprised a pre-reflex phase and a main phase. The oropharyngeal muscles and SH muscles were found to develop a pre-reflex phase specifically with increasing volume and viscosity of the swallowed fluid. Type I showed a different response to the highly viscous fluid in the older group compared to that in the younger group. However, type II showed concordant changes in the groups. Therefore, healthy older people were found to compensate for swallowing with a pre-reflex phase of muscle activation in response to increased liquid volume and viscosity, to adjust for age-related muscle weakness.

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