Chapter 14 – Analysis of Bioperiodicity in Physiological Responses1

This chapter discusses the analysis of bioperiodicity in physiological responses. Bioperiodicity is an integral part of physiological responses to nutrients and diets. A mathematical model can be used to establish the occurrence of rhythms and quantify the rhythm characteristics of components identified by spectral analysis. Deterministic, biological rhythms (chronobiologic rhythms) have four measurable parameters: the mean, amplitude, acrophase, and period. The periodicities in growth rates display infradian rhythms, and these rhythms appear to be endogenous. Chronobiological analysis gives new insights to relationships between nutrition and physiological response. However, certain procedures that interfere with recognition of biorhythms are: use of purified rather than integrated samples; use of large samples that appear to produce synchronous activity; and the search for homeostasis rather than perturbation. Recognition of these factors will improve understanding and interpretation of many biological experiments.