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Clinical Effects of Pollution
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
A 41-year-old vocational nurse reported a 20-year history of vague complaints associated with fatigue and mild muscle aches. A 2-year history of near-incapacitating, lower extremity arterial spasm resulted in absent dorsalis pedis and posterior tibial pulses. Incapacitating left gastrocnemius spasms, lasting several days, developed and required constant administration of Demerol and an antispasmodic to relieve the unrelenting spasm. The patient had a history of sensitivity to several chemical fumes, such as chlorine, perfume, pesticide, and cigar smoke, and to various drugs. This history and clinical course suggested environmentally triggered disease. The patient was placed in the Environmental Control Unit (EHC-Dallas) and, after 6 days without food or medication, all signs and symptoms cleared. When safe water was found, the patient had challenge in ingestions of single, less chemically contaminated foods. A typical example of the sequence of events during reactions was as follows: two bites of squash produced immediate vomiting, then generalized aching and malaise, and within 5 minutes, aching of legs with spasm and loss of the dorsalis pedis and posterior bibial pulses occurred. In the next 5 minutes, severe left pedal and gastrocnemius muscle spasm occurred with excruciating pain that required intravenous sodium bicarbonate and Demerol for relief. By the next 12 hours, noncontact cutaneous bruising would occur. The muscle and vessel spasm lasted for a total of 24–144 hours. Twelve different foods reproduced this sequential symptomatology.
Techniques in the Dynamic Modeling of Human Joints with a Special Application to the Human Knee
Published in Cornelius Leondes, Musculoskeletal Models and Techniques, 2001
The kicking type of lower limb activity is a rather complex activity that involves most of the muscles of the lower limb.25 The model shown in Fig. 3.16 is general enough to include major muscles associated with knee motion, namely, the quadriceps femoris, hamstrings, and gastrocnemius muscle groups.35 Any dynamic activity can be simulated with this model provided magnitudes, durations, and relative timings of these muscle groups are supplied. In this section, we will present preliminary results for the extension phase of the knee under the activation of the quadriceps femoris muscle group. The force activation of the quadriceps muscle group during the final extension of the knee is taken in the form of an exponentially decaying sinusoidal pulse. For a quadriceps force of 0.1 sec and 2650 N amplitude, the maximum angular acceleration of the lower leg reaches to 360 rad/s2 which is a typical value for a vigorous lower limb activity such as kicking.
Muscle energetics and electromyography
Published in Kumar Shrawan, Mital Anil, Electromyography in Ergonomics, 2017
Undoubtedly there is a close link between energy metabolism and excitation processes. Figure 5.3 summarizes possible metabolic and electrophysiologic consequences of muscular activity which might lead to fatigue based upon current studies. Prolongation and reduction in the evoked action potential have been reported during high-frequency nerve stimulation (Jones et al., 1979, Moritani et al., 1985a) or during ischémie contractions (Duchateau and Hainault, 1985), indicating a possible dependency on energy supply for membrane function or removal of metabolites and ions. Edwards and Wiles (1981) have shown that patients who are unable to utilize glycogen because of phosphorylase deficiency manifest a rapid decline in the surface-recorded evoked action potential amplitude and the failure of recovery during local ischemia following stimulated contractions at 20 Hz, which in normal subjects recovers rapidly. Furthermore, the depletion of extracellular Na+ has been shown to accelerate the rate of force fatigue in an isolated curarized preparation (Jones et al., 1979). This reduction of extracellular [Na + ] or accumulation of K+ may reduce the muscle membrane excitability sufficiently during high-frequency tetani to account for the excessive loss of force (Jones et al., 1979; Moritani et al., 1985a). In addition, Moritani et al. (1985a) have also demonstrated that the recording of intramuscular-evoked potentials showed the predominantly ‘fast-twitch’ gastrocnemius muscle to have greater reductions in the potential amplitude and conduction time as compared to those of the ‘slow-twitch’ soleus muscle. Thus, energy metabolism clearly plays an important role influencing neural excitation and electrolyte balance within the cell.
Specific collagen peptides increase adaptions of patellar tendon morphology following 14-weeks of high-load resistance training: A randomized-controlled trial
Published in European Journal of Sport Science, 2023
Simon Jerger, Christoph Centner, Benedikt Lauber, Olivier Seynnes, Till Friedrich, David Lolli, Albert Gollhofer, Daniel König
Mean rectus femoris CSA increased by +4.6% in the SCP group and +5.5% in the PLA group. Both groups showed significant muscle hypertrophy in the middle region of the muscle (SCP: at 20–80% of muscle length; PLA: at 20–70% of muscle length; Figure 3), with no group differences at any location. Other studies report an increase in fat free mass after supplementation with SCP, indicating that SCPs might have an effect on muscle hypertrophy (Jendricke et al., 2019; Zdzieblik et al., 2015, 2021). Different results for different muscle groups seem to be indicative of a muscle-specific effect. For the gastrocnemius muscle, we found larger increases in muscle thickness with SCP supplementation in a recent study with comparable design (Jerger et al., 2022). One possible reason for this could relate to the different relative involvement of the muscles in the respective training exercises. The gastrocnemius muscle is the predominant contributor to plantar flexion torque. In addition to the rectus femoris muscle, the other three heads of the quadriceps are strongly involved in knee extension, with the rectus femoris muscle having the smallest physiological CSA. Muscle hypertrophy could be distributed over the entire muscle volume and could theoretically be underestimated in this measurement. Following numerous studies (Centner et al., 2022; Seynnes et al., 2009), we nevertheless decided to analyze the morphology of the rectus femoris muscle representative of the quadriceps muscle for reasons of better visibility by MRI.