Chronotype and response to training during the polar night: a pilot study

Figures & data

Figure 1. Flowchart for the study design and the subject’s screening/selection according to the inclusion and exclusion criteria.

Figure 2. Mean values with standard errors of VO_2max in ml/kg per minute before (blue histograms) and after (white histograms) the period of training for E-types (n=3), N-types (n=5) and M-types (n=5), and all participants with valid VO_2max results (n=13).

Figure 3. Scatter plot with trend line showing the relationship between the percentage change from start of VO_2max as the dependent variable and the MEQ scores of the participants. MEQ score scale: E-type 16–41; N-type 42–58; M-type 59–86.

Table 1. Raw data for all the single participants (ID no.) before (pre) and after (post) the period of training.

					BMI		VO2max		Strength index		Flexibility index		Balance (seconds)
	ID no.	MEQ score	Age	Sex	Pre	Post	Pre	Post	Pre	Post	Pre	Post	Pre	Post
E-types	1	22	30	Female	28.1	28.6	31.5	33.26	179	231	275	262	80	77
	2	27	24	Male	22.1	22.6	41.8	44	294	269	202*	212*	100	57
	8	30	49	Female	29.8	28.3	29.1	32.6	184	164	364	289	63	66
N-types	4	47	42	Female	23	23.6	32.7	35	270	333	323	348	64	120
	5	48	26	Male	23	23.1	47.7	52.4	425	355	243	225	106	65
	6	49	46	Female	33.8	32.3	28.5	31	218	212	196	235	68	52
	7	49	25	Male	35.5	35.5	34.3	34.8	257	261	354	363	65	78
	3	50	45	Female	23.7	23.4	34.8	36.3	256	342	248	261	65	67
M-types	9	63	31	Female	23.3	22.4	39.5	40	223	349	283	290	67	66
	10	66	32	Female	30.3	30.3	39	41.8	220	271	237	221	70	68
	11	67	43	Male	30.6	30.7	33.5	32.7	260	329	73	83	66	64
	12	70	36	Male	33.8	31.9	29.6*	47*	294	381	207	213	65	66
	13	74	44	Male	31.3	31.6	39.6	40.7	273	383	148	174	65	80
	14	77	38	Female	19.3	19.4	51.6	52.8	424	447	296	251	120	88

MEQ score scale: E-type 16–41; N-type 42–58; M-type 59–86. VO_2max is in ml/kg per minute. Strength and flexibility indices were used to consider together three different exercises. *Not included in the calculations.

Table 2. Raw data for all the single participants (ID no.) for different flexibility tests before (pre) and after (post) the period of training.

				Left above (cm)		Right above (cm)		Sit and reach (cm)		Flexibility index
	ID no.	Age (years)	Sex	Pre	Post	Pre	Post	Pre	Post	Pre	Post
E-types	1	30	Female	25	25	30	31	25	21	275	262
	2	24	Male	25	21	31	28	6*	14*	202*	212*
	8	49	Female	38	13.5	25	29	41	38.5	364	289
N-types	4	42	Female	29	31	28,5	32	35	37	323	348
	5	26	Male	26	27	24	16	21	22	243	225
	6	46	Female	15	21.5	15	19	25	26.5	196	235
	7	25	Male	30	33	33,5	37	38	35	354	363
	3	45	Female	18	17	33,5	35	21	24	248	261
M-types	9	31	Female	21	18	29	33	31	32	283	290
	10	32	Female	18.5	18	20	20	28.5	25	237	221
	11	43	Male	–5	–1	6.5	3	17	19	73	83
	12	36	Male	9	8	17	20	31	31	207	213
	13	44	Male	5	7	19	20	18	22	148	174
	14	38	Female	31.5	17.5	26.5	30	28	25	196	251

MEQ score scale: E-type 16–41; N-type 42–58; M-type 59–86. Left above: shoulder flexibility left arm above; right above: shoulder flexibility right arm above; sit and reach: hamstrings flexibility; flexibility index: calculated score based on the tested values; see “Methods” section.

*Not included in the calculations.

Table 3. Results from Pearson’s correlation analysis between the MEQ score (MEQ score scale: E-type 16–41; N-type 42–58; M-type 59–86) and changes in fitness variables after 10 weeks of training during polar night period at 70°N, expressed as percentage of change from pre-test score.

Variables associated with MEQ score	Pearson’s correlation index
Percentage change in VO2max	–0.5287
Percentage change in strength index	0.4395
Percentage change in flexibility index	0.2667
Percentage change in flexibility (right arm above)	–0.0348
Percentage change in flexibility (left arm above)	–0.0127
Percentage change in flexibility (sit and reach)	0.3372
Percentage change in balance	0.0784

Figure 4. Scatter plot with trend line showing the relationship between the percentage change from start of strength index as the dependent variable and the MEQ scores of the participants. MEQ score scale: E-type 16–41; N-type 42–58; M-type 59–86.

Figure 5. Scatter plot with trend line showing the relationship between the percentage change from start of the different flexibility tests as the dependent variable and the MEQ scores of the participants. MEQ score scale: E-type 16–41; N-type 42–58; M-type 59–86. Blue dot and line: percentage change for left side; orange dot and line: percentage change for right side; green dot and line: percentage change in sit and reach test; yellow dot and line: percentage change in flexibility index.

Figure 6. Scatter plot with trend line showing the relationship between the percentage change from start of balance as the dependent variable and the MEQ scores of the participants. MEQ score scale: E-type 16–41; N-type 42–58; M-type 59–86.

Figure 7. Scatter plot with trend line showing the relationship between the number of participants attending group training as the dependent variable and the MEQ scores of all of the participants.