The “Abdominal Circulatory Pump”: An Auxiliary Heart during Exercise?

Abstract

Apart from its role as a flow generator for ventilation the diaphragm has a circulatory role. The cyclical abdominal pressure variations from its contractions cause swings in venous return from the splanchnic venous circulation. During exercise the action of the abdominal muscles may enhance this circulatory function of the diaphragm. Eleven healthy subjects (25 ± 7 year, 70 ± 11 kg, 1.78 ± 0.1 m, 3 F) performed plantar flexion exercise at ~4 METs. Changes in body volume (ΔVb) and trunk volume (ΔVtr) were measured simultaneously by double body plethysmography. Volume of blood shifts between trunk and extremities (Vbs) was determined non-invasively as ΔVtr-ΔVb. Three types of breathing were studied: spontaneous (SE), rib cage (RCE, voluntary emphasized inspiratory rib cage breathing), and abdominal (ABE, voluntary active abdominal expiration breathing). During SE and RCE blood was displaced from the extremities into the trunk (on average 0.16 ± 0.33 L and 0.48 ± 0.55 L, p < 0.05 SE vs. RCE), while during ABE it was displaced from the trunk to the extremities (0.22 ± 0.20 L p < 0.001, p < 0.05 RCE and SE vs. ABE respectively). At baseline, Vbs swings (maximum to minimum amplitude) were bimodal and averaged 0.13 ± 0.08 L. During exercise, Vbs swings consistently increased (0.42 ± 0.34 L, 0.40 ± 0.26 L, 0.46 ± 0.21 L, for SE, RCE and ABE respectively, all p < 0.01 vs. baseline). It follows that during leg exercise significant bi-directional blood shifting occurs between the trunk and the extremities. The dynamics and partitioning of these blood shifts strongly depend on the relative predominance of the action of the diaphragm, the rib cage and the abdominal muscles. Depending on the partitioning between respiratory muscles for the act of breathing, the distribution of blood between trunk and extremities can vary by up to 1 L. We conclude that during exercise the abdominal muscles and the diaphragm might play a role of an “auxiliary heart.”

Hypoxia and inactivity related physiological changes precede or take place in absence of significant rearrangements in bacterial community structure: The PlanHab randomized trial pilot study

“…The fact that mammalian hibernators returned to normal physiological status including insulin sensitivity during the physically active part of seasonal cycle despite overeating [ 68 , 70 , 71 ] is complementary to the alleviation of inactivity-generated negative physiological and psychological symptoms observed in NBR and HBR over 5 and 14 days, respectively, during the PlanHab wash-out period [ 13 – 15 ]. This period was characterized by increased (voluntary) exercise, establishment of hydrostatic gradients within body [ 14 , 16 ] leading to reintroduction of abdominal splanchnic circulation [ 72 ], significantly increased physiologic demands of the host, alleviated constipation [ 14 ], indicating that signals from exercise and muscle turnover reached intestinal tract as suggested before for athletes [ 4 ], animal models [ 73 – 76 ] and potentially primed functional capacity of healthy microbiome (this study (IEC, indole)).…”

The respiratory muscles during exercise

“…The abdominal muscles, together with the diaphragm, might play a role as an “auxiliary heart” during exercise. In fact, at each act of breathing a significant amount of blood, presumably from the splanchnic vasculature, is shifted between the trunk and the extremities contributing to increase cardiac output [ 14 , 15 ]. To a presumably lesser extent, lower limb muscle contraction contributes to venous return facilitating the propulsion of blood from the skeletal muscle vasculature, through the so called “skeletal muscle pump”.…”

Effect of core strengthening on cardiovascular fitness and flexibility in obese individuals: experimental study

“…Usually due to obesity overall activity reduces thus leading to shortening of muscles and increase fat deposition. 11 While performing exercises like reverse crunch, V plank, plank with oblique tuck, back extension etc. there is lengthening of one muscle group (hamstrings, rhomboids, abdominals, gluteus, etc) thus leading to improvement in flexibility.…”

“…During core strengthening exercises each muscle fiber extends to the full length of the muscle and performing certain core exercises also reduces regional fat in that area. 11 Apart from role in improving cardiovascular fitness it also reduce facet joint compressive forces and provide stretch to the lumbar muscles, ligaments, and myofascial structures. as stated by Gross and Worrell It also improves flexibility and enhanced flexibility has a greater effect on the range of motion and musculoskeletal injury prevention.…”