Cardiovascular and Cardiorespiratory Coupling After Different Types of Training and Detraining

The study of the cardiovascular and cardiorespiratory coupling (CVRC) is a hot topic in the medical literature focused to recognize the synergies that are present in healthy physiology [7, 8]. Several effects as aging [9], diseases [8] or mental state interventions [10] on cardiorespiratory coupling have been investigated, however, although its potential interest, there are no studies on the effects of training programs and detraining.

Two main types of training programs (aerobic- AT and resistance- RT) have been widely investigated by their important and different physiological effects [11]. Its combination (AT+RT), has been recently recommended with health purposes for extensive types of population [12-14].

The physiological effects of aerobic training programs has been traditionally evaluated through the cardiorespiratory reserve and the detection of maximal or threshold subsystem variables [1]. As a complex adaptive system (CAS), the human organism acts as an indivisible and integrated whole that cannot be reduced to the sum of its subsystems functions [2]. In this CAS the cardiovascular and cardiorespiratory subsystems are interdependent and interact in a dynamic and nonlinear way, i.e. non-proportional, which needs to be approached through nonlinear models [3], the study of time series and complex systems (CS) methodologies [4]. As the CAS enter every new situation with an existing set of capabilities [5] and exchange continuously information with their environment her/his behavior is unique and unexpected at short term (weeks, months) [6], the usual duration of common training programs.

In order to study the couplings and coordination between multiple variables in CAS, CS approaches propose the detection of the so-called order parameters, collective or coordinative variables, because they capture the order or coordination of the system [3, 15]. The principal component (PC) analysis is a common statistical technique that has been used to recognize such coordinative variables in a vast domain of biological research fields like: motor control [16], brain dynamics [17], DNA replication [18] or protein folding [19]. The PC analysis reduces the data dimension of highly coupled systems extracting the smallest number of components that account for most of the variation in the original multivariate data and summarize it with little loss of information. PCs are extracted in decreasing order of importance so that the first PC accounts for as much of the variation as possible and each successive component accounts for a little less [20]. The number of PCs reflects the dimensionality of the system, being a decrease of the number of PCs indicative of a major coupling (less dimensions) and vice-versa. The number of PCs changes when the system suffers a nonlinear change, i.e. a qualitative or coordinative reconfiguration. The PCs technique applied to kinematic variables has been successfully used to study the effects of motor learning processes [16], but has not been applied yet to study training effects on physiological variables.

The aim of this research was to investigate the dimensional changes of the CVCRC before and after a period of 6 weeks of different training modalities (AT, RT and AT+RT) and 3 weeks after detraining in healthy young men.