Effects of Nature-Based Intervention in Occupational Health Care on Stress – A Finnish Pilot Study Comparing Stress Evaluation Methods

Abstract

Purpose To assess methodology and its limitations for measuring effects of nature-based intervention (NBI). Patients and Methods Participants were 11 middle-aged female health care workers with lowered capacity to work. NBI included six group appointments in six months study period. Heart rate variability (HRV) and self-reported pain and work exhaustion were measured pre-post study period. Salivary α-amylase samples were collected immediately before and after three individual interventions. Salivary cortisol samples were collected on the same three interventions, on three consecutive days starting from the day of intervention, to assess (a) month effect (pre-post study period) and (b) day effect (intervention day vs non-intervention day). Results Individual interventions resulted in increase in α-amylase activity. However, the average fold increase decreased from the 3.05 ± 1.20 of the first intervention to 1.91 ± 1.00 and 1.46 ± 0.77 in the second and third intervention, respectively (p < 0.001). Cortisol concentrations were lower on intervention days vs non-intervention days, the difference being indicative (p = 0.050). Pain and work exhaustion decreased during the study period, as well as HRV, although any of these changes was not statistically significant. Conclusion For a large-scale study, it would be ideal to select assays for both major pathways: hypothalamic-pituitary-adrenal axis can be measured by cortisol, whereas response via autonomic nervous system can be measured by HRV, when roles of sympathetic and parasympathetic nervous systems can be pinpointed separately. Salivary α-amylase can be used when continuous monitoring is not possible. Psychological well-being of participants should be surveyed, as well as their activities and moods on sampling days recorded.

Using Heart Rate Variability Methods for Health-Related Outcomes in Outdoor Contexts: A Scoping Review of Empirical Studies

“…There were seven different types of outdoor intervention; however, over half of the studies were one-day forest therapy interventions [14,16,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. Other studies included mountaineering expeditions [41][42][43][44], forest therapy camps [45][46][47][48], green exercise [49][50][51][52], blue exercise [53], horseback riding [54], and skydiving [55]. Over half of the control groups had a similar exposure type as the intervention but in an urban context.…”

“…Table 4 summarizes the characteristics of HRV analysis methods used in the 34 empirical studies. Seventeen studies reported the HRV measurement period to be during the intervention [34,[36][37][38][39][40][41]43,44,48,49,51,53,54,58], and 17 studies reported the measurement period as pre-post-intervention [28,31,33,35,[45][46][47]49,50,52,[54][55][56][57]60,62]. Interventions had a wide range of exposure times, ranging from six minutes [40] up to eighty days [45].…”

“…Two more studies involved five to 12 days [57,60], with one study reporting an 80-day exposure [45]. Twenty-five of the studies did not report the use of a relaxation period before the start of the intervention exposure [31,33,34,[36][37][38][39][40][41]43,44,[50][51][52][53][54][55]60]. However, three studies reported a relaxation time of five minutes [29,32,35], five studies reported a relaxation time of fifteen to thirty minutes [28,39,48,55,58], and one study reported a relaxation time of two hours (60).…”

“…One device was used in three studies, and this included the Polar Electro models, RSS800CX [49,56], and S810i [54]. The following devices were used in two studies each: HeartMath EmWave Pro [45] and PC Stress Relief System [33], Zephyr BioHarness TM 3 [52,53], Actiheart [35,51], and Emotion Faros Sensor [28,49]. There were nine other devices used in only one study each, and one study did not specify the device used.…”

“…Almost every study used other physiological or psychological measures in their study, however five studies did not report the use of any other measures [29,32,45,46,57]. The three physiological measures that were most recorded included blood pressure (Bp) [28,31,[34][35][36]38,[40][41][42]49,50,52,53,58], heart rate (Hr) [28,30,38,39,42,43,[47][48][49][50]55,56,59,60], and salivary cortisol [33,37,[39][40][41][42]44,47,49,51,54,58]. Other less common physiological measures assessed were pulse rate (PR) [31,36,41,53,…”